Ah, the neverending thermal paste urban myth. We really should get Jamie and Adam to debunk it, although even if they blow up a bunch of overheated Macs, it won't have the same visual appeal of an exploding loo....
Undoubtedly, thermal conductive paste is key to proper heat dissipation, but given the assembly line approach of modern electronics, I would hazard to say that the probability of you getting a paste-less Mac is close to nil. The product is probably applied by a robot with milimetric precision unit after unit and not some poor suffering human drone with his or her finger dipped in the goo all day long.
However, if you're dead set on fixating that your Mac lacks enough of the stuff, go ahead and knock yourself out. The DIY for re-smearing the heatsink on yours is here http://www.ifixit.com/Guide/Installing+MacBook+Pro+13-Inch+Unibody+Mid+2010+Heat +Sink/4310/1 and here http://www.ifixit.com/Guide/Applying+Thermal+Paste/744/1 Be sure to have all the tools handy, work in a well-lit area, be sure no screws, springs or associated bits & pieces get left over and good luck!
yowza! that's a tricky bit of business there, and if in your opinion it doesn't need to be done, i'd rather avoid it ^^ the chance of screwing something up is too big, and not worth taking unless strictly necessary.
i'd love to see adam and jamie take 2 identical macs, scrape the thermal paste off one of them and leave the other intact, and run them.. until one melts dramatically (or some such thing). would be awesome!
anyway, besides high heat-sink temperatures (which doesn't really convince me as a sign of a lack of thermal paste) what are the signs that might indicate a real need for re-application of thermal paste? (if there are such things as real signs, ergo if the problem has actually ever existed).