Hi Guys, This definitely wasnt there before, no big deal but has anyone seen this before? If you look at the die, you can just about see it! Have i burned it slightly?
One of my XP-L also having this problem. Mine suddenly appear after reflow.
It wasnt there after re flow, but only thing i did was drive it on overdrive for about 60 seconds on the BLF driver. It got quite warm but not to hot to hold.
If it is a hard driven XP-L Hi, that is a big deal, a dark bit like that can absorb so much heat radiation that is may burn and make a mess of your silicon layer.
Theres no fixing it now! 
Ill keep an eye on it if it gets worse ill replace it.
Thanks
probably a flux spatter.try wiping it gently with a swab and alcohol.
and it will generate a hotspot and burn.
had one on an xml2.
alcohol(isopropal 91%) cleaned it right off.
Nah its definitely under the silicon!
Might sounds silly but try and wipe it of i had the same on my XPL-HI and i wiped it and it worked lol
Had a similar problem with an XHP-35 in the Acebeam K70 and it seems to be a common problem in that light. In my case I was able to clean it off by a combination of gentle scraping and cleaning with alcohol and swab (q-tip).
Whenever I see a mark on an LED I use an aspheric lens taken from a cheap zoom flashlight as a magnifying glass. If it’s on top of the LED I trying blowing it off with an air sprayer. If that doesn’t work I use alcohol wipes.
If it’s under the dome, then it is permanent damage to the LED. I’d discard that LED and replace it with a fresh one.
Cheers guys. I had to use some copper wire in the end to get it off it was really burnt on!