That was unexpected

There might be more to this and your bf just isn't telling you, i would't sweat it too much, there's a mission in just about every town, the cops might even have given him a ride there, they do that quite often in my town in those type situations.
You're a kind heart for caring about him leaving, trust in your bf, i know you two have had a tiff or two lately, do your own relationship a break by not harping on him leaving, let your bf know that you support his decision and then have some hot steamy sex with him, this will releave a stressfull situation and get things back on track.

chris

Chris is right Kimahri. If he was that shady, he could have had a warrant or worse and the last thing you need are police or bounty hunters at your door. My aunt took someone in like that and he had a bounty. When the hunters came for him, she opened the door and let them in rather than get her door kicked in.