760 turbo oil pressure light

Recentle ive noticed that as the car starts (first time, no unusual noises) the oil pressure light stays on for a second (almost as if a new filter has been fitted and takes a second to fill up the filter) It then goes out and never comes on again. If the engine has been turned off, and then fired up again an hour later, it goes straight out. If left for a couple of days without starting a similar thing happens. Ive been informed it might be the oil pressure switch? Other than that the car drives fine, engine sounds fine with no unusual noises. I also thought that maybe there is a pressure retaining valve of somesort? Any info would be useful!

MisterT. 

B230ET, I would try another filter , use a Volvo factory filter , its possible that the check valve in the filter is allowing the oil to drain back , although this can happen with Volvo filters but rarely. Mister T.