I see something similar, although I did not look into this in the detail you did (I compared mplayer playback to ffplay playback).
But I confess I am a bit more stubborn ( ? ) or perhaps have a bit more faith ( ? ) and don’t think this is an openSUSE-11.4 fault, but rather I am more suspicious of the construct of those mp3 and suspect there was a systemic error made in their creation. My knowledge in this is not strong enough to raise that to be higher than a suspicion.