D.B.
I don't give a few bugs much thought - I think they are part of our world and, if you can get past the "ick" factor, they are far less dangerous than most of the chemicals used to get rid of them. I think there are non-toxic things you can use - lots of people do that by creating recipes involving red pepper and so on. Google for ideas.
My main concern would be carpenter ants feeding off the wood in your home - sills, shutters, studs, etc. They are larger ants, but not the only large ant you see. And of course, if you see a swarm of ants with white wings crawling around, they aren't ants - they are hatched termites. But you're only seeing a stray one or two so that's unlikely. Try catching an ant or two in a glass jar or old plastic container and showing it to a professional pest person or two. Also check the yard for dead trees or trees with a dead section - sometimes carpenter ants live in the dead center of a tree and it takes a while for the whole tree to exhibit the signs.
One would hope that major problems would have been caught by the home inspector before the sale, but you never know.
Good luck.