Contractions during/after sex?

This might be TMI, but does anyone else have contractions during and after sex?
We had sex this last week (35 weeks) and every time I started feeling contractions during sex that lasted hours afterward.
I think it's just Braxton hicks, but is that normal?
I'm a FTM and I'm not sure if that's supposed to happen. They're only slightly painful at times, but for the most part I can just feel my stomach tightening and it's really uncomfortable. :/