I've noticed my '93 400E seems to downshift sort of abruptly when I am coasting (say, coming up to a red light which then turns green), going about 20 mph, then applying moderate throttle. There is a short lag (~0.5 sec) then a decidedly firm 3-2 downshift. Otherwise no shifting problems. Fluid is at the proper level, and has been changed religiously. Is this (I hope) just a normal quirk, or something to look into further?