Sounds like frustration and fear. I've had a few students who were so afraid of a checkride that they would rather quit. I got another instructor, someone older and somewhat intimidating, to give them a fake checkride. With the excuse that they wanted to check me as an instructor and see if I had taught them correctly and see if they really were ready for a checkride. After that I tell them that the examiner would be easier than that guy and what he just gave you was essentially an exact checkride.
If something in thier personal life has them in a bad mood and you know the flight lesson won't go well turn it into an oral.