Glass blocks renders weird when swinging your hand

When swinging your hand, Glass appears weird while it swings, but returns to normal shortly after

Tested on iPad Air (which wasn't on the device list, so I picked iPad 4 which is the closest model to it) running iOS 7.1b2

Any ideas why this could be happening? Can others reproduce the bug?

Edit: How was this closed as duplicate? This is the first post to report it. That other post is a duplicate.