Am I Normal?thoughts
I mentally correct people's grammar when they speak
Automatic grammar monitoring is an involuntary function of language processing — your brain parses incoming speech for errors whether you want it to or not. Whether you then suppress or act on the correction is a choice; the detection itself is not. Linguists call this 'prescriptivism' when it becomes a value system.
Have you ever done this?
Be honest — have you ever done this?
Related fact
Most 'grammar rules' people enforce (e.g. 'don't split infinitives') were invented in the 18th century by grammarians trying to make English mirror Latin. Actual linguists consider them stylistic preferences, not errors.