this happened to me big time last weekend and again late this week. i think they were moving the baby down, because my pubic bone hurt like heck the next day. they also (i think) started to dislodge my mucous plug, because i had a TON of discharge the next day. so much so that i thought my water had broken at first, and i even called the OB. but she said to give it a few hours and see if it continued or let up, so i didn't have to go in. and it totally let up, so i'm glad i waited. the next day i had some stringey mucous, which made me realize what was actually happening. tangent, sorry, but if you have a lot of discharge today or tomorrow, it could be that.
either way, exciting! definitely means our bodies are getting ready.