Keep an eye on those head bolts. They can loosen up over time. Heat cycling will cause them to be loose after a fresh rebuild so you may have them get loose on you again. Head bolts, intake, and exhaust bolts are all things that should be double checked before a ride. I may not check them on every run around the block, but I will always spend 10-15min before a big ride making sure everything is tight as it should be. I just had a shock nut vibrate off the bike recently, thankfully while stationary and going over things anyway. Mopeds are fun like that.