I have in the past and always assumed it was because your body shape changes so the forces applied to/by certain muscles is different. If that's the cause it should clear up as muscle strength improves. I mentioned my pains to a physio at work and she gave me some strengthening exercises which did work but I didn't see a benefit for 3-4 weeks. If its really painful or lasts a while...or if you're otherwise concerned I'd see a doctor.