i'm a jerk

as i was leaving work today, a blind man in front on my went through the doors and paused. i realized he was holding the door open for me, even though i was a little ways behind him. he said, "i thought there was someone behind me," as i went through. i warmly thanked him, and he was really nice. it made me feel really good but kinda bad at the same time. why the nice blind man have to be so nice to now i feel bad for all the times i haven't held the door open for someone!