Thermal Pastes And CPU Heat Sink?

Just a quick one (hopefully). The fans in my PC have been making a lot of racket and I was checking them and cleaning them today and trying to pin point which one was kicking up such a racket.During this I removed my CPU heatsink/fan and gave it a clean, but I wondered if I need to reapply thermal paste? I know when changing you're supposed to put it on, but I thought that as I have removed it, but not changed it, the paste won't be as good a contact between the CPU and the heatsink and won't disperse the heat as well (or maybe hardly at all?)Just checked the temp with only Firefox (and background tasks of course) running, and my Q6600 is running at about 45, 45, 45, 58. The final processor is always the hottest and it says the max it has been was 70.I'm loathe to do to much with the PC (gaming and I've got some videos to transfer to DVD, which always pushes one of the processors) if the lack of paste could damage the processor.