When you make a direct warp tile and give it a push block flag, it turns into a block that when stepped on, gives link the dive animation, and then teleports him back to the place he started in the room and takes away a quater heart.
Images:
Push block vertical/direct warp a
Are you sure it's set to a Direct Warp Type? If so, which letter, A, B, C, D, or Random? Because I myself am not seeing this behavior. You may want to post the quest in which you saw this.
I am 75% certain he chose Dive Warp by mistake. I mean, those two are right next to each other.