Coco Worm discoloration

[gabbreanna]

Hi all,
My Coco Worm had developed red discolouration at the top of the tube.
It seems happy enough otherwise.
Any advice on what this is?
First pic is example with no light on.
2nd 2 pics taken last week.

 

[Mr. Mojo Rising]

Hi, can you point out what you mean with an arrow or something? I don't see anything concerning, I'm missing it.

 

[gabbreanna]

Ok so in the two bottom pics the whole top white part of the tube is clean and white. Then this morning I notice the very top rim on the white tube has gone red. It might be nothing but I wanted to ask