Bitter APA

So I did my first 5 gallon AG batch and it seems to have a lingering bitter aftertaste. Not sure if it is the hops or perhaps tannins.
Here is the breakdown. It has been in the keg 4 days.
Whatcha think?

Primary 3 weeks. Secondary cold crash with gelatin one week.

Test APA 5 gallon
10-A American Pale Ale
Author: Landon
Date: 5/3/09

Size: 5.0 gal
Efficiency: 75%
Attenuation: 75.0%
Calories: 155.75 kcal per 12.0 fl oz

Original Gravity: 1.047 (1.045 - 1.060)
Terminal Gravity: 1.012 (1.010 - 1.015)
Color: 6.52 (5.0 - 14.0)
Alcohol: 4.6% (4.5% - 6.2%)
Bitterness: 36.4 (30.0 - 45.0)

Ingredients:
7.0 lb 2-Row Brewers Malt
2.0 lb Crystal Malt 10°L
.5 oz Chinook (11.4%) - added during boil, boiled 60 min
.5 oz Cascade (6.3%) - added during boil, boiled 30 min
.5 oz Cascade (6.3%) - added during boil, boiled 20.0 min
1.0 ea WYeast 1056 American Ale
1.0 tsp Irish Moss - added during boil, boiled 15 min

Unless you are sensitive to harsher bittering hops, and Chinooks are pretty harsh, I wouldn't think that this brew would be real bitter. The BU:GU is 0.77, which is pretty balanced, also you've got 2# of crystal 10L, which should add sweetness.

Yeah, your beer will be on the bitter side because of the chinook hops. Those are high alpha hops and you won't find them in beers with S.G. below 1.060 very often. If you use the Tinseth method for calculating IBUs (wich I think is the most accurate method), I get 45 IBU for your recipe. For a 4.6% beer, that's pretty hoppy. You can try to let it sit a bit. Time takes the sharp edge off of hops. It's only been in the keg for 4 days after all.

Try it again at the 3 week mark or even longer. I think you'll find that all the flavors will meld and it will balance out.

What is your water profile like? I believe water that is very hard and high in calcium can bring out a harshness that is undesiarable in lighter beers. But the water geeksD) can give better details on that. I know Yooperbrew has talked about having this issue in her brews, before getting her water figured out.

Not sure about the water profile. But I figured it was the chinook giving off the aftertaste. It's certianly not a bad beer, but I was jsut curious considering it was my first AG 5 gallon batch.
Thanks.