Cage Discoloration After Wearing

I removed my cage for hygiene purposes after wearing it for a day. The parts covered by the device have turned slightly purple, while the uncovered areas retain their usual hue. Does this seem typical? It’s completely painless to wear in everyday conditions, though I do feel some discomfort during an erection. I suspect that all those erections throughout the day are causing the color change. Once I showered, the discoloration faded back to normal.