Loose RAM would certainly cause crashes, as would dirty contacts. It may well be that you have cured a very minor problem by reseating the RAM.
In years gone by, when RAM came in the form of about 32 seperate chips, part of our regular maintenance was to push all of the chips firmly down into their sockets with our thumbs. They had a tendency to "walk" out of them due to constant heating/cooling cycles. Sure made for a sore thumb. At least now RAM has clips to hold it in place.