Rammus has a hidden stealth skill?

I've played a few games with an enemy Rammus on their team and every single time he comes to gank, I don't even see him walking down the river or bush. He just appears right infront of me and I don't have enough time to get out. This has happened with 1 other player who actually fought against our Rammus and he complained about not being able to see him running through the bush or even into lane. I don't know if this is a known bug or not, but I'd really appreciate it if you'd fix it. I don't want my teammates thinking I'm bad because I can't even see an enemy walking up to me.

[sg-ahri-1]

;Edit;

The bug is alot like in this video, close to exact! https://www.youtube.com/watch?v=wdJ7f2KgyxA