I've not experienced leaks but recent valve adjust exposed me to the way Honda seals up head covers on the 3.5. There's really only one way for a leak to develop and you've likely guessed correctly - the seal itself is kaplooey. They are a two piece assembly of seal and metal cap slipped over a self seating bolt. See image below.
I didn't attempt removing the seals from the bolts - cuz I had no leaks - but toying with them, I'd guess there's a certain technique for moving the "rubber" seal past the seats at the end of the threads. The flare probably makes removal easy but sliding the new seal on might be a challenge. The center of the seal is hard material and will likely need sillycone lube to let it slip over. I glanced thru FSM but didn't see anything specific other than inspection and "replace seal".
Check to make sure but I believe Honda PN: 90442-P8A-A00, "Washer, Head Cover" fits 2006 thru 2014 3.5's. $3.78 from cheaperhondaparts.com
https://www.cheaperhondaparts.com/o...GdlbGluZS1zZWRhbiZ5PTIwMTQmdD1ydGwtc3Vucm9vZi1uYXZpJmU9NS1zcGVlZC1hdXRvbWF0aWM=
Best of luck
EDIT: your seeping doesn't look too bad. Suggest keeping an eye on things until valve adjust time - make it one project. Use a mirror and good shop light to get eyes on the rear valve cover too. If you have seeping back there - and it's not too serious, you'll want to address valve adjust and oil leaks in one project. Make sure to check around cover edges @ the head surface too. You can see most of the rear head cover from under the truck.