Oil Pressure dropped

if you have a wet gauge, it could have air in the line. if it has a sending unit, it could be bad, but not likely. as long as you have over 25 lbs. it should be fine. low oil level will let it drain the pan(not completely usually) and loose pressure. p/d pumps will cavitate if starved. but, not likely either. my 340 has 25-28 at idle cold. and 23-25 hot. 45-55 at cruise rpm hot, and 65-75 cold. don't freak-out. if you have a leak though, you need to get that fixed. you know earth day and all that frilly fru fru crap.