US-05 and sulphur?

I made a blonde last fall of which I am just now finishing up the last couple of glasses.

My notes made at racking and kegging indicate it had a pretty strong sulphur aroma. I also noted on my spreadsheet that I found it odd that the supplies of dried yeast at the LHBS I visited for this batch were all kept at room temperature in the shop.

I also made a couple of other choices on this beer that I will not likely make again for an ale like this. First, I went with all pilsner (domestic) for my base malt. Second, it was my first use of Citra hops. The hops for this beer were 100% Citra.

I've given it a few months in the keezer, drinking a couple every so often. Keeping the temps in the low 40s with about 12psi (so about 2.3-2.5 volumes).

Overall, my impression of this beer has been "meh". It does not taste "bad" per se. But the aroma and flavor, while not overtly sulphury, make me think of the strong sulphur aroma I caught at kegging time.

So a couple of questions:

1. Could to brew shop's handling of the US-05 be the source of my frustration with this beer? I pitched the mrmalty.com-suggested volume of rehydrated yeast for this beer. I pitched and fermented at 65F, left the beer on the yeast for a little over 3 weeks (all primary) and did all of my transfers under CO2.

This is the first time I have ever caught sulphur aroma/flavor from this yeast. I made an IPA a few weeks before this beer with US-05 (stored in the fridge at a different LHBS) and got the neutral profile I expected from this yeast.

2. What about the citra hops? Everything I have read on the variety is that it should be clean and citrusy. Is it possible that the yeast just overwhelmed the hops (kept the IBUs in the low 20s since it was a wife beer)?

3. What about the grain? My grist was 78% pilsner; 8% carapils; 5% 10L crystal; 5% vienna; and 3% acidulated malt (I have an alkalinity problem in my local water that I offset with minerals; distilled water dilution and a little bid of acidulated malt)

I mashed at 152F for right at 60 min. I was showing conversion (via iodine) at the 60 min mark and started my batch sparge.

Could my heavy use of the pilsner robbed this beer of some of the sweetness I might have gotten by using standard 2 row or a little more crystal?

My first inclination is to go with the yeast and its handling. Looking for either affirmation of one of my listed culprits or help in identifying another possible suspect.

The two big suspects for sulfur are typically yeast stress and DMS precursors. Both sound plausible enough in this case, but my hunch is toward the latter. Room temperature storage will gradually decrease the shelf life, but dry yeast is relatively robust. Unless it was getting baked in direct heat or sat at room temp for a long time, I doubt you'd run into major problems.

With that much pils, though, I would typically boil for 90-100 minutes. How is your boil? I'm going to assume you don't keep the lid on the pot when you boil, but that would obviously be a source of problems if you did. Is there any other off flavor, particularly one that tastes like canned corn?

No DMS present that I can tell. I generally do a 75-80 min boil leaving the lid on only long enough to get the boil started. Once I get the boil going, the lid comes off and it's completely open for my whole boil.

I used the 11.5g packet (1 full packet) when I pitched. Per mrmalty, I should have only needed .8 of a packed. I wonder though. I didn't check the packaging for dates on brew day.

I still have another packet in the fridge that was purchased the same day (has remained unused because I suspected it was the problem). Best used by date on it is 2 of 2012. So age should not be in a factor. The shop keeps its dried yeast at room temp (low 70s) in plastic storage bins (the kind that is a collection of small plastic drawers)

Maybe the pils is it. I brewed a lager the next day with pilsner malt from the same bag. It's a better beer, but still decidedly "blah". I usually go for heavy beers that grab you by the throat and slap you around a bit to get your attention. Perhaps I just brewed something I didn't like.

The sulphur thing still throws me a bit though.