Microaggression

I once witnessed microaggression.  I over heard someone telling a man that one of their mutual friends was gay.  To this the man responded, "Really?  He doesn't seem gay."  This was very wrong of the man to say this.  He was assuming that everyone who identifies as gay are the same.  He is assuming that they ast the same, dress the same, talk to same, etc., when in reality this is not true.