I've never encountered this before.
When it's turned on, it shows the standard blue color. The editing behavior works as it should, I'm just curious about the GUI. I have checked the manual and internet, there is no mention I can find of this behavior.
This occurred in a PT 11HD session. I quit, reopened the session and it still happens. It does not occur when opening the same session in PT 10HD. Just for kicks, I created a new session in 11HD - Yep, the orange still shows up.