The front, pointy end of the saddle somehow hooked onto the back of my shorts, right above when the chamois departed from my hiney. As I swung, up, the tip of the saddle held the chamois (and my shorts) down. I went up, my shorts did not. AARRGGGHHHH.
I have Pearl Izumi's... and this happens to me on occasion too! I thought it was just me.

Well, I always move myself back down the minute the padding gets caught... so I don't moon anyone... but you aren't alone in it getting caught.

This even happens with my Peral Izumi's that are TOO TIGHT on me.