Zyra Ult Bug

Was playing ARAM just 5 minutes ago, when I got pulled by a blitz into a bush and I ulted, the animation and the damage was applied, but as soon as i spawned again (20 secs) my ult still looked available even though its cool down was 93 seconds. I was not abel to cast my ult however, it a visual bug that makes it look as if you had your ult, when you really don't