Will a Vlamingi bother a birds nest?

3 weeks ago I picked up a pink birds nest frag. Day 1 I noticed my Vlamingi tang pick at it. I figured maybe because it was new or the tang saw something on it to pick at. Week and a half later the frag branches are thickening and coloring up, but it does not appear to be spreading out. The ends also seemed white, like fresh breaks but I thought I was imagining things.

Then I found this

The vlamingi is my first suspect. The only other I could think would be my coral beauty? Everyone else is tame. Yellow and purple tang, chromis, and firefish.

Any idea who it maybe, and if moving the frag to a different area would help? Thanks