Dropping in unannounced and claiming "they were just passing by" is one of JWs favourite weapons.
Catch you in an unguarded moment, have you at a disadvantage etc. I view these drop in visits as a kind of spiritual litmus test designed to gauge how hospitable and receptive you will be to them, so they can measure that all important spiritual "health." I hate them too, so intrusive and rude. Like the secret police turning up at the door.
Though, if you are trying to be reinstated it's not completely unexpected, that they would call in.