I guess it's possible, but it's also possible while you were out someone did say "patties" and you heard it while your son didn't. I can't really tell as I was not there. Like someone already said, just be a little extra diligent on monitoring your symptoms for a bit.
I wouldn't be too concerned though; it didn't seem too extreme even if it was a hallucination, but if it was it could get worse so again, just keep an eye out.