Mine does it when relaxing & it's a bit cool, the code is - front paws apart + ears on back = "please do not disturb".
House rabbits can also feel cold with sudden temperature changes. Mine asked me to put the fire on, I took a photo after, of a cold bun warming his bum!
I find that there is a broad "code of standard behaviour" but it has been very modified with us, according to my response, & the same behaviour can mean different things in different situations.