Obi-Wan does remember the incident: 9-year-old Anakin was barreling down the hallway at full speed (he had possibly had a little too much sugar that morning, possibly because he’d discovered Obi-Wan’s secret candy stash, and also he’d maybe snuck a few sips of Obi-Wan’s caf, and he’d just started learning about how to use the Force to run really really fast) and there came the group of younglings rounding the corner, holding hands in a cute little Baby Jedi Train. Anakin’s precise point of impact was a 3-year-old Togruta girl, who stood up, dusted herself off, and kicked Anakin, hard, in the shin, because YOU’RE NOT SUPPOSED TO RUN IN THE HALLS, LASERBRAIN.
The master leading the children around had scolded her, because deserving or not, a Jedi is not supposed to strike someone in anger, while Obi-Wan picked Anakin up off the floor, hissing that this is what happens when you don’t have patience and look where you’re going (while thinking that he was going to have to get a padlock for his candy stash.)
Anakin didn’t understand how a little tiny kid like that could kick so hard.