Seems his new habit has struck a nerve at school too: I got a notice from his teacher that ALL the 5th-grade teachers have complained about his "meow" sounds: it distracts his "squad," makes him very annoying to interact with, and people are starting to worry that something's really wrong with him.
Gabriel has a long history of annoying his class with constant, repetitive, inappropriate sounds. In kindergarten, it was "POP goes the weasel!" and in 1st-3rd grades, it was the nonstop humming. He seemed to get a handle on it in 4th grade, but now his tendency to express whatever sounds are coursing through his head have a feline manifestation.
I talked to him at length about it, explaining that it wasn't just me being annoyed at his grating sounds -- now people are thinking there's really something wrong with him. I know there isn't, but I told him that he really, really, REALLY has to stop it. We shook on it....then I made fun of his floppy handshake, and he laughed and gave me the firm one of a young man.