Could very likely be a "drop off" ..... someone who had it, didn't want it, for whatever reasons, and took it for a ride to a new town. As opposed to a stray from another neighborhood out for some "catting around" on the town before heading home.
If you determine it to be a stray, and if you plan to keep it, I would certainly take it to a vet for a good physical exam. Fleas are the least of your concerns with a stray that happens by. Cats are carriers of parasites that you really do not want to come in contact with.