I know when we were one month behind on our mortgage, someone came out apparently and made sure we were still living here and hadn't jetted. It was just one of those things the bank did (we got caught back up, was just a slow time for DH, and that was one bill that slipped
) The bank just sent someone out here to drive by, and possibly photo, and then charged us $50 for it. We paid it, but it was irritating - we had already called to inform them that we would be late, and that both the previous month and current month payments would be made on X date.
But, I'd go with something nice like they liked your house and wanted to reference something about it for theirs.