Residue on LEDs???

[renoeb]

I have an old reefbreeders fixture that I have been using over my frag tank for about years now.
I looked at it recently and the lenses/beads covering the diodes appear to have a brown/black residue just on the end of each (they are not the large lense, but the standard tiny ones that are affixed to each diode"

I have not tried to disassemble the fixture yet, I wanted to see if anyone else has experienced the same thing before I did.
I'll try to get pictures asap

Thanks

 

[Reefing Madness]