I had cramping around my scar area during my second pregnancy too, and honestly it was quite unsettling. That said, scar tissue can be sensitive and stretch differently as your uterus grows, so some discomfort is pretty common, but it's really important you mention this to your gynae at your next visit just to make sure everything is okay with the scar and the pregnancy itself. They'll want to check it out properly, especially since you're planning another delivery and they need to assess if you can attempt a vaginal birth or if another caesarean would be safer. Better to get it checked than worry through the pregnancy.
Absolutely normal. Now after 8 months of my second c-section I still sometimes feel icky to feel the scar