Age of consent is the age you can consent to sex with anyone. If you are under the age of consent, you cannot legally consent to have sex (in the US). IANAL but I believe it is even legally blurry if two people under the age of consent have consensual sex, would technically be guilty of statutory rape (since neither of them could legally consent). However, the law is not really worried about those cases, so by and large nothing comes of it. But technically speaking, under the age of consent you cannot legally consent.
Reads more like playful jabbing rather than actually accusatory. People do it all the time, where you may stop doing a bad habit and people ask “Are you okay?” in a joking manner. It could go the other way, but that’s not how I read it.