The gauge only goes up to 70 psi and it's normal for the V6 to bury the gauge when it's cold only, once it warms up it will still hit 50 psi a lot and idle around 30 psi which is normal for the 3.6 it has a high pressure/ high volume pump for it's 5 miles of timing chains needs tons of oil dumped on them.
The V8 will not bury the gauge ever.
So if you were running a constant 65psi in your stock LS3 or L99 you would have an issue, probably a pressure relief valve issue...not good.
No dog in this fight anymore.
5th Gen owner 2009-2016.