Gallery gaskets already replaced?
 

Any tips to identifying whether my gallery gaskets have been replaced by a previous owner on my 2009?

Whsts your oil pressure at?

Not sure if there's any way to know this without opening the engine. How many miles you got now?
I explained this in a different topic, but basically what you can do is just install an oil pressure gauge and monitor there - if your oil pressure is always above the FSM prescribed minimum, then you're basically fine and you don't have to worry if gaskets were changed or not. If the pressure is lower, then you can suspect you need to change these.