Look pedals - Q-factor drift?

Hi - Quick question for my DH.
DH had the Q-factor (generally: distance of the pedal from the center line of the bike) out of alignment b/t his two pedals. He corrected the pedals last Spring. Noodling around the driveway this evening, he noticed that the Q factor for his left pedal was off (before, it was his right pedal). He hasn't touched the pedals since he corrected it earlier.
Do any of you know if the Q factor on Look CX6's can float or come out of alignment over time through pedaling action??
Thanks all.

The pedal body on the pedal spindle could be loose due to wear or other problems such as bad bearings. The pedal spindle itself could be unscrewing itself from the crank arm due to the above or not being threaded properly. Or the crank arm could be loose on the bottom bracket. If it's the bottom bracket itself you would have noticed long ago because it would have been wobbling, creaking, grinding and generally misbehaving.

One last thing, were the crank arms recently removed and re-installed? With square taper cranks, you can jam the crank arm on too far. Even with splined cranks, the crank could be loose even if you think it has been tightened down properly.

Thanks SadieKate, But I don't think it's a crank or BB issue. It's not the spindle coming out of the crank arm. It's the pedal drifting out the length of the pedal spindle. The spindle remains fixed in the crank. One of the features of this particular type of pedal is adjustable Q factor. DH has tightened them down, but he's just not sure if there's some minimum it should be torqued to or if there is some issue that could be happening at the pedal/spindle interface that could be causing drift.