Teemo - Homeguard - Boots of Mobility bug

Hey, I noticed this bug because it seemed very weird- As I'm running out of the base, the speed is supposed to slowly diminish until it's 0. But (maybe because of the relatively high movement speed?) as soon as I get outside of the base, I notice that I still have about a quarter of the time left, but it will just instantly disappear. I noticed this because instead of a slow decline into my movement speed, there is a sudden "lurch" where I instantly slow down. It's nothing much, but it makes me feel like I am going slower than I should be!!

Thanks!!