Is it a bad idea to give my bunny cheerios?

i've had my rabbit in the kitchen for an hour or so the past few nights as it's so cold, just to warm him up a bit before he goes in his hutch. i spilled some cheerios on the floor this morning without realising and he ate them. he seemed to enjoy them, too, but is it a bad idea to give them to him as a treat every so often? he was much more enthusiastic about the cheerios than he was about his cauliflour. of course he has rabbit food as well as fresh fruit and vegetables every day. can he eat 'human food' on occasion for a bit of variety or should he just stick to his rabbit food?