Could be, although it certainly takes long enough to charge. I've also noticed that happening on my rig with the larger battery (feeding a dummy load, but also into my old Rat $hack 20-006 when in the Faraday cage in the basement as proof-of-concept.) Didn't do it when I first acquired the batteries but has developed over time. This only seems to happen when running high-power on UHF, and becomes more pronounced the closer I tune to the centre of the band (450 MHz.) This has not happened when running low power on UHF or either on VHF, in any mode when using six Energiser "Recharge" 2300 mAh NiMH AA batteries (1.2V) in the AA tray, or with the stock rechargeable battery.
Mine's primarily used as a receiver, but this is something I thought rather odd. At least I didn't pay a lot for the 3800s and rarely key up (especially at high power), so personally I'm not too concerned, but I can understand how this would be a concern to others.
sq3hopeFD, did you get your batteries from "Expert Power" on Amazon, by chance?