LED tint shift ? (not drive current related)

I got a XIAOZHI with 3C tint a couple weeks ago from FF. Since then, I have run it on high and med for extended periods and dropped it once on concrete, but it survived with minimal damage.

When I first compared the beam to a BLF Mini, the tint of the XIAOZHI was a purer white and made the Mini look a little greenish. It had such a clean white tint that at times it was hard to tell whether it was cool or neutral without another reference (partly because 3C is on the cooler side of neutral).

Today, after I put an o-ring in front of the lens, I tested it and I noticed the tint looked different - much warmer with a yellowish hotspot. Now compared to the Mini, the Mini looks whiter overall including the hotspot.

I don’t know if the tint shift happened today or if I just noticed it today, but I’m pretty sure it has changed. I’m not sure exactly what caused it though. I didn’t try to de-dome it or anything, but it could have been the drop or something that happened when I took out the pill and reinstalled it. If the dome is still intact, the phosphor shouldn’t have been disturbed right? I tried taking the o-ring back out but that didn’t make a difference.

Any ideas what could have caused this? Anybody have a similar experience with unexpected tint shift or am I just going crazy?