yea it does dry up, and if it was manufactured (ie by hp) they LOVE to put this flap of foil tween the cpu and the heat sink, which just doubles the chances of heat sink compound separating (xbox360 cough cough)
and if you have the side off, just go poking around until you find something hot enough to make you notice
just dont press down too hard and short the board out (and watch them fans, they eat finger tips)