A neighbor keeps asking me if im O.K. with a smile on his face....?

A neigbor keeps asking me if im O.K. with this dirty smile on his face and it irritates me. That kind of question seems meddleing if clearly nothing is wrong with me and besides if someone is concerned why would they be smiling? I lost my temper with him-not physically-and started to say "let me tell you something...but he handed me the 5 bucks he owed me...so i was thrown off and blew off the incident. Is asking someone if they are ok with a dirty smile on their face taking liberties?