Yeah I pulled a bit on it and it definitely glue, but mine doesn't seem strong at all :D...Half of the ring doesn't seem to have a drop of glue on it strangely, and where the glue starts it comes off easily. The grill is coming off to the point where you can see behind it. I really don't want to send them back to china so I'll probably just glue it back myself with something removable.
Maybe it's a sign that you should do the regrilling mod. The grills are literally stripping themselves for you.