You probably feel like you're over burdening him and thats why his reply feels the way it does to you.

I agree with farmergirl. There's nothing in his reply that sounds unusually angry or upset or annoyed. BUT, if it still bothers you, can't you tell him that you're worried maybe you're asking too much of him and see how he responds. You ahve to be willing to listen to his answer though..... even if it is, "This really is no problem, don't worry about it."