Do i have to much air psi. in my oil tank?

[shvy]

hi i have a 1989 2302 trophy w/a with a 1998 250 hp mercury EFI outboard. after i go out to do some fishing and come back (about 6-8 hours) get home wash it down, park it in driveway. then go over and check erery thing out elec., fluids, and so on. when i go to fill up the oil tank it seams to have a lot of air psi. more then 6-8lbs psi. is that norm or is their something wroung? how would i check the air psi. been pump in to the tank. tis a 3 gal. tank.

Shvy