That’s not bad at all. I have owned GPU’s (220) that only had 15Lbs at idle and they still ran for years. I don’t know what the Text book spec’s are for aircrafts but in the automotive world and the bearing manufactures as in Federal Mogal, Clevitte, Speed Pro, Acl and Vandervill ect all recommend 10 pounds of oil pressure per 1,000 RPM. I myself do get a little uncomfortable when oil pressure goes below 25Lbs at idle.