Makes sense to me. What's the redline on that motor? I'm guessing it's an electronic gauge?
Rule of thumb says 10 psi for every 1k RPMs. Granted your motor probably has a bunch of miles on it so to not be perfect is expected.
My 440 has about 20-30 PSI hot idle (depending if I've been beating on it hard or not). It's usually all in around 2500 RPM or so, and bumps up to about 60-70 PSI IIRC (usually not watching it that intently). Granted my motor is fairly new, but the tolerances were also all on the loose side.
As long as it's not knocking or doing anything weird, I'd probably run it.