different sync offset while in record?!?

[tomcat]

just to add another crazy variable to this unsettling fw sync offset mess, i recently finished mixing a feature completely in the box (junebug, screened tonight in the comp at sundance. Wish us luck!) where, for the very first time, things looks out of sync when pt was recording the mix. It was sort of funny. the director would say "hey wait, does that look soft?" then i would stop recording and play it back and he would say "oh, it's fine, i must be getting tired." I didn't keep him in the dark for long, but i was pretty embarrassed to say, "gee, that's wierd, i never saw that happen before". Protools is always interesting. I still dont' know why this happened. It was an HD2 accel, g5 dual 2 gig running 6.7 with a canopus. I would rock back and forth between input and "tape" and everything looked good, but when i would punch in, things went about 2 frames out (late, i think). When i would play back that same track i just recorded, it looked fine. baffled.