I'm 7.5 weeks with what will hopefully be our 5th baby. With DC3 and 4, I had definite tightenings from 12 and 10 weeks or so, respectively.
I was just walking across the kitchen and got that unmistakable, painless tightening for a few seconds. 
Despite previous MCs, it's not concerning me- I just wondered if anybody else had tightenings/ Braxtons very early on?