I gained 400 xp from the practice tool

I don't have an image because I didn't see it at first but I played as Draven and was just messing around. Keep in mind I was level 21. So I decided I would grab a couple of Dragons and destroy the turrets with attack speed or attack damage. I killed MF a couple of times and all of a sudden exiting, I get the screen for leveling up. I didn't think of it really my brain brainlagged until I left I noticed that I gained 400 xp from just Practice tool. Tried to recreate it again and It did not work. Did anyone have this happen? If you did please tell me which champion? If it does happen we need to get this fixed because It could cause massive not legit level upping/farming.