Probably tight boots - maybe sciatica left that area a bit numb & you were leaning harder than detectable? Do your roller ski wheels spin freely or is there built-in friction? Have you ever fiddled with them in that regard?
My RS have built-in friction for a purpose, otherwise they are too fast which makes it harder to balance say for a V2. The friction should also be optimized for getting a good workout for double-poling on a level road. Last time I needed my highest friction level on my stopper for a steep downhill; and during the second half I kept it at the second lowest level, as opposed to the lowest level, which is the default, in order to get more workout on my double poling. When I purchased them from Ed D. there was a choice as to the default friction, and I chose the typical one (don't remember the details) that he recommended.
Wasn't aware of Ed's making RS with adjustable friction when I bought mine. Oh well,
I'm nothing fancy anyway:-).