Hard to say for sure but yes it's a possibility the mechanic did something wrong such as incorrectly changed your derailleur limit screws as part of the installation, installed the master link wrong, etc., etc., or it could just be coincidence. That's why you'll be encouraged to do your own work by posters here. Nobody cares about doing it right more than you, the owner of the bike and you can spend the time necessary to double check everything and it will give you the knowledge to sometimes spot trouble before it becomes catastrophic. Just sayin'.