Afraid I Ruined My Batch With Pecans

So I started a Maibock last night so I popped open a few of my Vanilla Pecan Porters that I brewed about a month and a half ago. It poured with great head, at least 2 fingers on top and it was maintained to the bottom of the glass, beautiful.
The thing is that I couldn't get over that it had a slight sour smell, and SWMBO said that it tasted a little more bitter than before. I thought it tasted fine, but the smooth vanilla flavor was definitely toned down and the bitterness was a little more, but not unpleasing. I drank two of them, same sour smell and slight bitterness.
So my question, could this be because of the residual pecan oils are going rancid, or maybe its because it should age longer? Or maybe those two bottles got a slight infection? There was some gunk at the mouth of the bottle, but I think thats because those bottles were stored upside down for a little while.
Please share you thoughts, I still have about 25 of these bottles left and I'd hate to pour them out!

Drink 'em until you can't stand the taste any more, then cook with 'em!

Why were you storing your homebrew upside-down?? You silly goose.

greencoat said:

Why were you storing your homebrew upside-down?? You silly goose.

Click to expand...

Ya, the upside down was a mistake, last time I ask the GF to help me box up brews for storage

Wait a minute, you brewed a vanilla porter a week ago, put it into a bottle and just opened it????

And you wonder why it tastes like crap????

wow major typo. i bottled 5 weeks ago and brewed it back in december

Revvy said:

Wait a minute, you brewed a vanilla porter a week ago, put it into a bottle and just opened it????

And you wonder why it tastes like crap????

Click to expand...

Exactly true! A little over a week after brewing and your drinking them?

el_bandito said:

Exactly true! A little over a week after brewing and your drinking them?

Click to expand...

Again, sorry for they typo, I bottled 5 weeks ago, brewed it early Dec

if it is indeed an infection, i'd drink them quickly.

in my experience, sourness only got worse.

Vanilla fades, so that might be part of the problem. Sour isn't rancid, at least to my taste buds. More likely there's an infection.

The weird thing is that the 'infection' if that is it just appeared all of the sudden. No problems in either fermentation and any of the other bottles that I had before last night. Maybe its just an isolated incident and I got a few mediocre bottles... Lets hope...