stuck in my ways

ok so last week i went to the grocery store and it was crowded like always but there’s this one checkout lane that’s usually empty because everyone thinks its far away, but id been using it for years cause i know all the shortcuts. anyway, i start scanning stuff with the self-checkout and then i notice another customer has been waiting behind me forever in a line. i kinda freeze because im not sure what to do next - should i let them go before me? or should i just finish cause its way faster for just 5 items? idk. so i end up finishing super quick but the look that guy gives me is like pure hate. it was weird cos he looked older than me and kinda reminded me of my dad who always taught us to be polite in public spaces, not to take shortcuts when others are waiting. now im thinking if maybe i should have switched lanes or something. still dont know if its a big deal but keeps bugging me