its been a while since i've been to this forum.. wow a lot has changed! i'm happy to finally see an entire section dedicated to bunnies
vivien your rabbit's adorable! it's normal, the flopping thing.. they do it when they're secure and contented. it's also known as the Dead Bunny Flop, my buns do it all the time too
http://furrybutts.wordpress.com/2008/07/07/dbf/