That's a good question to ask. Honestly, it isn't below what the manufacturer indicates as a problem, so even though it is low, it won't likely make noise. With the engine hot and at idle (1,000 RPMs) the minimum recommended is 6 PSI.
If you look at the pic below, it shows what the minimum readings should be with the engine at operating temperature and at specific RPMs.
Let me know if this helps or if you have other questions.
Take care,
Joe
See pic below.
Image (Click to make bigger)
Sunday, May 23rd, 2021 AT 7:07 PM