I've had that exact pain since about 26 weeks- it's kind of a jolt, isn't it?
I'm now 40 weeks 2 days, and my baby definitely isn't engaged yet (COME ON!!!!!!) but in our scan at 39 weeks 6 days, it was revealed that he/she had his/her hand up above his/her head. So I think there's been some poking going on.
Pesky infant.