Look for ears back, and sharp skittish movements. That's a sign that your bun is upset or scared. But if the ears don't stay back and his movements aren't tense, then he may just be checking your puppy out. When I got a new bunny and introduced it to one of my bigger older buns, the little bunny would sneak in close, or dart in to check my big bunny out, then dart away. As she was more sure about my big rabbit, she would stay closer longer, and then when he finally licked her, she felt safe and followed him everywhere after that. So just remember that the puppy and bun don't speak the same 'language' and so it will take a little time for them to get used to how each other communicates. So your bunny probably isn't doing that behavior so that the puppy will chase him. He's probably just trying to quickly check your puppy out and see if he's safe. It might be good if you get your pup to lay down and sit still so that your bun can safely check him out. If your bun does in fact want to play chase, you'll see your bun stop and look over his shoulder after darting away, to see if your puppy is following him. You'll just want to make sure your bunny has some safe places to get away from the puppy, and you supervise to make sure the puppy doesn't try to play rough with your bun.
