Yes checked mine against my travel one just in case. The front tyre was also left at 36psi so it's only the rear they keep blowing back up to 42.Last year checked the accuracy of my tyre pressure gauge against three other gauges. They varied by 7 PSI at a reading of 30 and 3 PSI at 50.
Bought a new one and checked it at an engineers shop and know to add 2 PSI to the reading. Checked it again after 10 months and it is still giving same readings. May be worth checking yours.
I'm sure 42psi. is the two-up setting. Not sure why they would default to that without asking the owner what he needs ? Maybe they assume it's easier for the average owner to lower a pressure than it is to inflate.Stay at the recommended pressure, a couple of pounds either way's ok , but 42 lbs is way over the top,