Good question. You would have to think that a hook has been weakened by doing this. However, I've done it plenty of times on hooks that have bent out only slightly and have never experienced any problems.

I find a 1/0 SL12s hooked into a stalk of ecklonia kelp and pulled aggressively with a 20lb fluoro tippet will bend out a bit before releasing or ripping the kelp out. Used to happen lots when I was guiding. The trick of hovering your fly just above the kelp is a skill that can be hard to learn for a new client.