Nothing in that section of the sump. My pump are all external pumps to the sump.
I thought the same thing a stray voltage in the sump the only device submerged in the sump is the heater which based on the tempature before the issue and after would have been off at the socket level.
Someone playing a trick on you? Very odd, I can't find any other posts about this issue? I guess if it never happens again, no worries, but still would be nice to know exactly what happened