We had a brief problem with Wendys bike once where it did that. It stopped after a couple days but that is what promted me to make my first gauge. Her oil pressure was fine but we would have never known that without one. Turned out she has sprayed water directly on it when washing and that caused the problem.

I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!