Cho' Gath Ultimate's (Feast) CD won't reset.

Hello, I regularly play Cho , so a couple of times recently I found this problem.(Video related) When I use R (Feast) on a minion to devour it, and at the same time an Ally tries to kill it, because he is faster than me, I would not take the kill of course, meaning I don't take a Feast Stack, but the CD on R would still apply for it's full length. If this is how Cho's R is supposed to work then you should ignore this thread. IF not then please enlighten me. Thanks.