I'm not aware of any particular "gotchas", but I've basically taken the same approach in the past with NPBs. Usually I'll just re-list the item and leave the NPB a negative. I would imagine that there is a method for marking the item "paid" on your end.
As I see it, if the winner hasn't either paid, or contacted me within a reasonable amount of time (especially if I have to contact them first), all bets are off. (I've been more careful these days about mentioning a "timeframe" for payment, usually 7 days.)