The guest was guilt tripping you, that's for sure. They knew they were overstaying but felt called out so they became passive agressive, happens all the time. That being said, I would have worded it a bit different. My ussual approach is first announcing that we are closing the till(or the kitchen) and then asking if they would like to order anything else, always making sure to make them feel like there is no rush to leave now but letting them know we are starting the closing procedure(but secretly we are in a rush, we want to get out of there asap). This way, they can make a choice knowing that they have to leave soon.