huh? I think it's normal, depends though. Are you fit? How's your core strength?
Personally I think it's normal and just means that those muscles were in use...
But. Know that all the force and effort should be well distributed as many complain that their wrists are sore or back, and so on. Make sure you are fitted and adjusted to whatever is appropriate for you and everything should be good. No one thing in particular should feel overly ridiculous...
However, if you are fit and everything's fine... Then it should all be good and your muscles are just "getting used" to it. lol $10 I'll be feeling the same in the next week or so as I haven't ridden in a while after my accident.
Good riding!