Pillar knocked my car's rear bumper

Was reversing out of the church building at Angela's workplace last week and I assumed it was clear behind since I recall there was only 1 car and it was parked rather far away. But I forgot there was a pillar and next things I knew that pillar 'knocked' the rear bumper. It was quite a hard knock but thankfully there was very minimal damage. Only upon very close inspection then you will see there is a scratch. So I will just leave it and if any unlucky person were to rear end and cause some damage to the rear bumper which warrants a replacement, I can save some money!!!