Noki

I got this as well, though I was shifting? Relogging fixes it though

Did you spawn the endermite via enderpearl or spawn egg? Because I recall that endermites spawned via egg were intentionally immune to the endermen's aggro. Correct me if I'm wrong though, I can't seem to find the bug report for it.

They do turn purple, just fade back to red, and the red that is there is much more desaturated