Guilt, Dry humped when i was little

This has been bothering me alot lately,i am a 28 year old guy and recently i remember when i was little kid, one morning I went into my younger brothers room and rubbed up against him, dry humped when he was sleeping, i wanted to know what it would feel like but it felt strange so i stopped. it was odd and i didn't give it much thought, it only happened once and that was it. but now years later i randomly remembered it and i feel so guilty. i keep telling myself that i was little and i made a mistake but i still feel bad, sometimes i feel like crying. I try to distract myself and it works sometimes, playing video games or hanging out with friends but the guilt comes back. I want to apologize to him but it have been so many years and he was asleep so he wouldnt even know that happened. I dont know what to do,