oil press warning

[feelstranger]

Hello all,
I have a question, but first the story...
Last week the SO was driving the 200 on a hot day along the Mass pike and had the oil pressure warning light beep at her several times.  She pulled over several times and checked the oil etc (smart girl).  It was fine (I know the light is not for the level - she may not have).  She kept going and she said that when she shut the AC off it never did that again.  She made it to Saratoga (in none to great mood) when she picked me up and we drove back to VT with no warnings and the oil pressure stayed in the 5 range while motoring.  It has acted normal up till yesterday.
So I get in the car and start it up (first time for the day I think)  and the oil warning goes off.  I look and see that the pressure appears pinned at the 5 position at idle.  I seem to recall that the pressure sits a little high just after cold starts - but maybe not....?
I shut it down and restart and it goes of again - I let it idle and it goes off and I move it to get the other car out and have not driven it yet.  
So the question is...  Will over pressure tip off the warning?
Are there any known electrical issues with this system?
I really get the feeling this is a gremlin but maybe that is just wishful thinking.
I'm running 20w 50 dino oil. 

Thanks for any input.
Nat