Oil Pressure guage

mine does the same, and recently goes very low after warm at idle. I'm thinking prob. pump is almost worn out. But it's lasted about a yr or more doing reg oil changes. Seems to be more common when i've exceeded 2 months or 2000 miles. If yours is doing anything like that try an oil change and a napa oil filter i found they have a little more room and are better filters then the fram