Need help diagnosing cause of acetaldehyde/phenols/lactic acid

So...

Got the score sheet back for my Cascade gold ale. The cool thing is that I got 9/12 for aroma and 3/3 for appearance but got schooled on flavor 8/20. I got docked because one judge mentioned "dry sourness apple-like" and marked the acetaldehyde off-flavor, and the other mentioned "dominant plastic with sourness" and marked acetaldehyde, phenolic (plastic), and sour (lactic).

I took copious notes from this batch, so I was wondering if some of you might be able to help me prevent this in the future. First, let me list the recipe.

Batch size: 2.0 gal
Boil size: 3.0 gal
Efficiency: 80%
OG: 1.040
FG: 1.008
IBU: 24.8
SRM: 4.1

2.0 lb pale 2-row
0.5 lb carapils
3.0 oz crystal 10L
0.5 lb vienna

0.2 oz Cascade 7.1% @ 60 min, 15 min, 5 min
10 g Cascade 7.1% one week before bottling

Nottingham Yeast

Both judges suggested yeast health as a possible cause for acetaldehyde, so let me go ahead and list everything related to yeast and primary fermentation. First, it was primary only, and due to the fact that this was the last batch I made before I made a fermentation box, I used a swamp cooler and kept the temps below 70F at all times for the first week.

Pitching - 9 Aug 2009:
Rehydrated 11g nottingham at 85F for 15 min. Cooled to 67F, the temp of the wort. Due to unexpected low boil-off rate (0.5 gal/hr), initial wort gravity is 1.032. So, boiled 0.4 lb of LD Carlson Briess DME pilsen light in 1.3 cups water. Cooled to 69F and added to fermenter.

Gravity reading - 16 Aug 2009:
1.009 @ 79F

Dry hopping - 23 Aug 2009:
Grabbed another sample and added 10g of the Cascade directly to fermenter.

Clarifying - 27 Aug 2009:
Bloomed 1 tsp knox gelatin in 3/4 cup cold water for 15 min, heated to 180F, cooled 15 min, poured in primary

Bottling - 29 Aug 2009:
Boiled 100g corn sugar in some water, poured into bottling bucket, racked beer through autosiphon into the bucket from primary. Filled bottles as usual through bottling wand.

Gonna bump this one.

well it sat on the yeasts long enough.Unless you either over/under pitched(which it doesnt look like you did).The only thing I could think of is having it sit at 79 may cause some phenols(not usually after that long),but I don't think there would be any more acetaldehyde left in there.Did it taste like it?It's a pretty noticable flavor.

To be honest, I don't seem to be able to distinguish a lot of these flavors and aromas. For example, they both said it had a very bready aroma...doesn't smell at all like bread to me. I tried hard to notice the green apple flavor, but again, it doesn't taste like green apple to me. However, I can taste some sourness. It's not like vinegar though, just a little tart and leaves the tongue a little dry.