Ask him to point it out to you next time it happens, or make a note on his phone, so you guys can discuss it. Not making excuses but I also forget specific examples sometimes lol, so I do both of the above. It may also not be intentional re what he said, sometimes we can unknowingly shift our tone when we’re annoyed but children pick up on that so easily. Sounds like he’s probably just concerned and u guys can work through it together.
If he can’t explain what he’s talking about, what does he want from you?
Is he the type of person to gaslight you for his own amusement? To make you doubt yourself just so the spotlight isn’t on his ‘bad’ parenting, if you’ve ever called him out on anything before?
Tell him the next time he notices to say something then and there. Otherwise leave you alone
Neena has a great point. To me personally it sounds like he's projecting his own insecurities onto you. If he can't provide a valid discussion, call it for what it is.
Maybe not angry but condescending? I’ve noticed when I’m annoyed the tone or mannerism in which I speak while not angry or mean aren’t the nicest