It is a new engine? There are so many variables from a bad
oil pump to a problem with the bearings. Drain the
oil and open up the filter(s) look for signs of trouble.. Aluminum / copper might indicate bearings. Steel or iron could be an
oil pump or it could be crank material.. It seems unlikely since there were no sounds associated with the drop.
I had a crappy oil pump on a rebuilt 428. It never dropped on me like yours did but I wasn't there for the maiden voyage.. I did have a little higher pressure but my oil pressure maxed out at 38-40.
I pulled the pan, found no damage, replaced the oil pump and I have 75 psi on start up and 45-55 under idle, normal driving conditions. Pull the pan see what there is to see. Inspect the oil, pull a main cap if need be.. Good time to install a windage tray if you didn't have one put in. Try replacing the pump.. It worked for me.. (shameless plug, but I have a new High volume pump listed with a few other things in Parts for Sale)