When you have an experience that has a single negative detail and you dwell on and suffer over that one detail more than any other aspect of that experience you are doing mental filtering. I do it sometimes. It's hard to get my mind off that one negative. I think that's partly due to the fact that I, like many people, have grown up in a culture that teaches us to try to eliminate failures and mistakes in our lives, so we tend to notice and focus on them. However, there is a difference between noticing a mistake enough to change and avoid making it again and focusing on that mistake and beating yourself up about it for days, weeks, months or years afterwards. The former is being clear-eyed and on the road to improvement. The latter is called identifying yourself by your errors.
I think it's clear that identifying someone we know by her errors is one of the heights of disregard and cold-heartedness, that doing so makes it even harder for that person to have hope she can change or live an error down. We know that for the vast majority of people, including you, loving-kindness, not error-rehashing, is what enables them to change for the better. But those of us who wouldn't dream of doing that error-rehashing to others often easily do it to ourselves.