red to yellow!?!?!?

This one is blowing me away. My 98 beetle's left rear tail light has never been hit or taken apart. I have had this tdi from when it was new until now. My daughter was following me and later she said I should look at my tail light. I had her step on the brakes while I was behind and the left rear was yellow and right rear red. I just laughed because I thought I had put it in wrong after changing a bulb. I pulled it out again and its not possible to put it in wrong. Is it possible for the lens to change color on its own? I swear its all yellow, top and bottom. The right side is normal, top yellow and the bottom is red. You guys reading this are probably going to suggest that I should be locked up for my own safety and quite honestly I don't blame you for thinking that.

red to yellow

How much egg-nog had you consumed?? lol

Did you put in a yellow bulb for the brake light bulb?

TW