What's wrong with my bunny?

I got my bunny today from a pet store. He is only about a month old and he is very very small "dwarf bunny" The problem I am having is we have let him out of his cage to hop around our apartment and he is pardon this but " pooping" alot and when I say alot I mean alot he is not even out for 10 minutes and it is all over the floor. he has been doing this since we brought him home around 7 and i am not sure why. My mom said that he is probably really scared and he is really young. I do not know I am just worried that there is something wrong with him please help.