Please HELP! My belly is super firm today! What does this mean?

I am 39 1/2 weeks pregnant. Through out my entire pregnancy my stomach has been,, hmmm, I guess you could say squishy. That's the best word I can come up with. However, today when I woke up it is firm as a rock. Normally, if Kyler (baby) has his foot pressing against me and it hurts I can just poke it and he will move. Now I can't even poke his little foot because my finger goes no where. When I was pregnant with my first son I had to be induced at 36 weeks bc I was suffering from severe preclampsia and had no choice. He was born completely healthy (7lbs 11 oz. 21 in long) so he came home with me the next day. I have never experienced the "end of pregnancy" you could say. So is this normal? Does it mean anything? Oh ya, I went to the doctor on Tues. and found out I was about 2 cm dilated... if this means anything. Thanks in advance