It happened to us twice last year, both at TS restaurants. It truly was not a big deal at all--I looked at the receipts to check to make sure the number of credits deducted was correct, and noted the error. I politely returned the receipt and my KTTW card to the servers, explaining we were using DDP credits, not room charge. It only took them a minute or two to correct the error. Really, if you know how many credits you have (and I did--I tracked them obsessively) and you check your receipts after every purchase (TS, CS or SC) it shouldn't be a problem.
If you're still worried--check your hotel bill on the tv frequently or decline room charging privileges on your cards. Or even just decline on one card--we do not put charging privileges on our kids' cards (for obvious reasons), but they have full access to DDP credits, so we could just use one of their cards to "pay" for meals.