M.R.
I think almost any ache and pain is normal. If something is ever unbearable it is a good idea to check. I remember lots of "loosening up" aches in my lower back and those being especially uncomfortable. Your body's already done this, so sometimes it is just a little ahead of itself. Some cramping is also normal, again from things shifting around, growing, etc. Any aching accompanied by any spotting or bleeding is worth a quick call to your OB just to check. Congratulations! :)