Strange faded out Levenger True Writer FP

[mge01park]

This is believe it or not my beloved True Teal Demonstrator Fountain Pen weirdly faded out. I can post the RB if you want to see the difference. Weird! I have a ridiculous amount of these instruments and never saw this before. By the way, it’s not ink (and not used as an eyedropper) 😊 as I found it this way recently OOB unopened from quite a while ago. 

[Penguincollector]

  Could it have been affected by sunlight, or heat?  

[mge01park]

It was in the original box which was in a office storage file box and in A/C all the time. I've been buying these since the 90's and never saw this but i understand that it can happen but I thought with more exotic materials like celluloid, or ebonite or resin.