Reason I said check the actual pressure first, is A) it's easy, B) the sender was out, and may have been dropped, and C) I have certainly seen LBC gauges that were far from correct.
For all anybody knows, it was reading high before the rebuild with horrible tolerances, hence "looked" normal.
Second is relief valve, as Lord Knows we've seen that happen.
But, until you have empirical data to support going further, I always want to know what it actually IS.
To wit: I have a couple of gauges for oil on my Jag, one was reading very low.....checked pressure mechanically, it was fine.
Sender replaced (leaking anyway), no change. Swapped the dash gauge, it now reads close to mechanical, and I am happy.
In another marque, I have boxes of oil senders and water temp senders, usually match them to a gauge by A) mechanical oil test and B) thermostat in tank.
They are not all necessarily "bad", just have variations that I match to the variation in the dash gauges.
In a shop, you immediately go for the relief valve instead of actually reading the pressure, you'd probably get fired.
You would then have no idea what it actually was before you changed out the relief valve.