Does he need treatment or leave be?

Hi all! Noticed today my bristlenose looks like he has an abrasion on his back. He’s 5 years old, always grumpy so darts around fast from one hide to another. I have got 2 new hide/ornament things, put in approx 5 weeks ago. I did try to feel inside and rub down any rough/sharp bits but I wonder if he’s caught himself on something I missed? Perimeters are amm. 0 nitri 0 nitrate 4. He’s the biggest fish in the tank, just small fish (danios,tetras,guppies etc) 260L tank. It doesn’t look sore at all but just wanted to make sure he’s ok to leave be, don’t want to not do anything then find out I could’ve saved him if he died. Thanks in advance

Clean the filter if it hasn't been done in the last 2 weeks. However, if the filter is less than 6 weeks old, do not clean it. Wash the filter materials/ media in a bucket of tank water and re-use the media. Tip the bucket of dirty water on the garden/ lawn. Cleaning the filter means less gunk and cleaner water with fewer pathogens so any medication (if needed) will work more effectively on the fish.

Do a 75% water change and gravel clean the substrate every day for a week. See if it helps. If it doesn't, then post more pictures.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.