I've *never* had an oil filter loosen up on me and that, combined with the missing bolt, and overfilled oil, it all points to a problem in the service department at the dealership.
Changing the oil is easier, not to mention cheaper, than driving the bike over to a shop, waiting, and returning home- or having to get a ride and make two more trips!
This is why I like to work on my bike. I get that isn't everyone's thing, but many times I think we become intimidated that we'll make a mistake, so we end up paying someone else to make the mistake. I care more about my bike than any mechanic, and some are just watching the clock til closing time.
Glad it wasn't something worse.