Allright... Look, if the guy says they were sliding out, then they were sliding out. Thing is, it's not the rule... it will be a definite exception. The dude knows if he's telling the truth, and since you weren't there to see it (or to not see it), there's really no need to take him to town over it. He might be exaggerating...
Getting pissed off at this is a also little silly since you didn't build the bass! Don't take it personally.
For my own part, the Peaveys I've owned have been fine basses; and I'll admit that since they weren't Fenders or Rickies, and I was once young and stupid, it took me a while to get hip to Peavey. But now that I am, I am sold on the ones I like. My present Dyna Unity is really a great bass, with a unique and musical "personality".
Whatever, no need to flame him.