As the title of the thread asks, has anyone else noticed this?

To set the record straight, I'm admittedly a big guy in the hips, but I never have any issue fitting comfortably into an AA economy class seat, and I can always wear the seat belt with plenty of extra length to spare, as well as comfortably lower the armrest without infringing my seatmate. That said, I've noticed that the seat belt lengths in First Class actually seem to be *shorter* than those in the Coach cabin on many AA planes. Specifically, this oddity seems to be especially prevalent on the S80s, 757s, and 762s (J-class). I've never perceived this problem on any of the NGBC seats, nor any economy seats on any AA aircraft, including Eagle flights. However, on the S80s, 757s, and 762s, I usually have just enough belt to buckle with virtually no extra to loosen it.

Why would you use a longer seat belt on a thinner Economy seat, and then use a shorter seat belt on a wider seat in First?