Garen Walking Through Walls

Last night I was playing a ranked match as , everything was fine for almost the whole game. At one point I activated my Q and began chasing a in the river. he popped a ward and hopped to it, over the river wall by Baron which is normal, but then I just kept chasing him. I don't know how, I just ended up walking right through the wall. This was the only instance of this glitch that I saw, but I felt as though it should be reported. I'm sorry I don't have video evidence. I had ShadowPlay turned off. When I play tonight I'll make sure ShadowPlay is enabled so that if this happens again I can have proof.