I had a similar experience with a beer I made a couple months ago. I used 2 oz. of chinook hops for the bittering. About two weeks after bottling it had a very intense bitter taste on the back of my tongue. I was concerned that is was almost too astringent. Now, just a few weeks after that the intense bitterness has mellowed considerably and now it seems just right.
It makes me wonder how those insanely hopped beers out there keep their intensity over time.