I would NOT use lock-tite. Those screws are small. Just tighten them up and you should be "good to go".

I have a couple of 625's (my most shot revolvers) and I haven't had any problems with the screws loosening. One thing all Smith's are prone to is the ejector rod loosening. You DO want to keep an eye on that. Just check it from time to time (I check mine every time I clean it). Other than that, it shouldn't be a recurring problem. They were probably not tightened enough from the factory. Do not over do it - just snug them up with a screw driver that FITS. I use replaceable tip screw drivers and am particular about good screw driver fit to avoid marring the screw heads.

FWIW
Dale53