headlight cracks?

i was wondering how this happens? the cracks are on the inside of the light so i am a little confused i didnt think that plastic could dry rot but that is kind of what it looks like? i dunno if you can see them or not but both headlights look like this

 

Did you paint them? They look like they've had the BHLM done to them and the paint is cracking.

 

no they haven't been painted which is why i was wondering what could cause this? the same thing happened to my brother's charger headlights and his aren't painted either. i am gonna replace them soon anyways and do the blhm and retro's so it really isn't that big of a deal. i was just curious to see if there is something i could do to avoid it or does it just happen sometimes?

 

if they havent been painted does that mean they are aftermarket BHLM? like Ebay ones?

 

The headlight bezel looks black, did you buy the truck aftermarket or put Ebay headlights in there? The part that looks like it's cracking should be chromed plastic if it was bone stock.

 

i just checked and i guess the previous owner did do the bhlm and failed epically lol i didn't realize the oem ones are chrome on the inside