Did I abuse my brother

Hi,
For the past couple of years I was suddenly inundated with an unbearable amount of guilt over something that happened 11 years ago. However, lately it has become almost debilitating. When my brother was 4 and I was 9 we were playing around. Due to how long ago it was I don’t know what the full details are or what instigated this but I hopped on top of his legs and began dry humping them (we were both fully clothed), after Several seconds he told me to stop (or something along those lines) I continued for a few more seconds before stopping. This never ever happened again. I love my brother, we have a really good relationship and I never wanted to have sex with him or harm him in any way. The whole scenario lasted for about 20-30 seconds. I am so repulsed and feel so guilty about it that it keeps me up at night. He has never mentioned it and leads what appears to be a very normal and happy life. I just compulsively worry about what I’ve done and whether or not it may have harmed him. As his older sister the last thing I would want to have done is abused him.