Mine is a week 25, and I have no problems, either. It is dependent upon location, not the week it was manufactured.
Are you in an area with generally good AT&T reception?
Week 30, signal plummets with death grip.
It is definitely dependent on location. At best I get 4 bars at home, but it will drop to 1 on command.
Nope not always. I'm in the LA area when I'm home but I work for an airline and travel to a lot of podunk places (i.e. nowhere Nevada, Kansas, Montana, Nebraska, etc.) and so far so good other than just the typical poor reception I always get out there pre-iphone 4.