Possible teleport bug on new Rift

Was laning top as Garen vs Mundo, got the kill and pressed the turret with a group of minions. Turret was targeting minions. When Mundo began casting Teleport to return to the turret, with minions still in range, the turret auto focused me as soon as the animation for teleporting to it started. This occurred on the northwest 1st blue side turret in top lane.

Anyone else experienced similar? This can't be an intentional change to the teleport mechanic.