Cannot process events error

[theAVator]

I was animating a model I have, and noticed that some labels I applied to taillights weren't showing up. So I edited the material and  went to reposition the label so it showed correctly. When I hit ok, it throws this error.

What events is it talking about?
Why does it say the hierarchy is being modified, if I'm not doing anything to the hierarchy?

If I just delete the label and re-add it, will that solve the issue?
Thanks!