I have had exactly this problem with my Fritschi Freerides but only twice in about 15 days of use (so far). I have had the bindings checked and they are fine apparently.
I suspect that it was due to ice on the boot because it has only happend after I had the skis off for a while; once after a 20 minute boot back (I know, I had touring skis so why was I booting… anyway...), the other time was after I’d skinned up but I did wander around on the summit for a while taking photos etc. Both times I seemed to pop-out very easily on the slightest impact (e.g. small bumps and very small drops - I don’t mean cliffs I mean 30cm drops on to a cat track). When it did happen it happened more than once in the day and always from the same foot.
The fact that it happened several times in one run and then didn’t happen again for several days makes me think it was icing on the boot. Also my boots are pretty worn, so there is room for ice to build up and not prevent me clipping in to the binding if you see what I mean. I am hoping new boots will fix this, plus I always take extra care to completely clean my boots now when ever I step in to the bindings.
On other occasions I have skied bumps and rough terrain with the same skis and boots and had no problems at all.
The really annoying thing was that both times I released I was with guided groups, so I held up the group while I searched for a lost ski and of course there is no point in trying to tell the others that it wasn’t a wipeout, you can never blame your gear can you