set point of Red dot changing on it own?

I have a nice Holosun red dot mounting on my modified Tanfoglio 45acp. The pistol has been my favorite for the year or so I have owned
it.  Today, the vertical setting was off by 4 inches at 10 yards, and who knows what at 20.  I have several Holosun dots, and
never had this happen.  I had to get out the hard rest and reset the dot which required almost 360 deg turn of the adj screw on
it. I don't see any likely mechanical reason, everything is rock solid, but I wonder if maybe the internals got wonky or perhaps
the electrical spirits were upset?

If you're the original owner, you may be covered under the warranty.

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