After you brought this up I did a bit more digging. What I read was the magnetic compass would swing in alignment with the magnetic field (caused by an energized pitot power wire ) and stayed put.
But whatever the cause, the next time I rent an airplane I’ll give it a check just to be certain. Better safe than sorry.
Thanks for the suggestion.
I haven’t flown without a handheld GPS for backup since the mid 90s. I still have my old Garmin GPS-90. Slow as molasses, but it still works (data is years out of date).