I would have to guess that the sea foam loosened some gunk up and clogged up the sensor or sensor passage. I have used sea foam in a number of applications from back firing 2 strokes to the lawn mower to cars and trucks and have never lost oil pressure. I have had to pull carbs apart and clean them though from all the gunk the sea foam loosened up.

1988 2DR 5SP 2.6l Monty. Balance shaft elimination kit installed. 120k miles. Timing jumped, pulling motor to see what needs to be done.