Doubt it as well but it's a possibility. I wouldn't drive on the highway if the car isn't running properly. If you have to drive it fast (on the highway), then don't drive hard. I would start with a pressure test. Maybe the timing belt is loose and it jumped a notch. I would make sure everything is lined up to TDC (top dead center) first. It's free to check and takes 10 minutes. If it is, I would suggest a pressure test. If the pressure test says it's holding pressure, then take it for a rip and see if there is just something gunked up.
Rule #1 though, do not get mad at the wife. She's probably very nervous to ruin your car when learning so the last thing you want to do is discourage. When I was teaching my girlfriend, she was bad. She was saying she didn't want to ruin anything. I laughed and said I'll just fix it, it's only a car.