On the flight from San Antonio to Corpus Christi, a yellow number on the engine monitor caught my eye. The video below shows what was happening. The engine seemed unaffected & fuel flow was normal. Turned the boost pump on, and the pressure increased, but continued to fluctuate by 10 psi. Switching tanks had no effect. Posted this to the pa32 group, who mostly seem to think it's normal. I don't think it has done this in the past, but until I dump the engine monitor I can't be certain. I do think I would've noticed a yellow number if it had happened before. Any ideas? There's a mechanic on the field. I'm not crazy about turning a random mechanic loose on it either, but it's making me nervous.