This is why I love this community! The response to this has been incredible
I will definitely put it in the mail for you guys today (it's coming from a sailboat in Hawaii so it might take a bit). I did not post photos before because I couldn't figure it out on the fly via mobile on my first post, but I'll throw them in here.
To answer most of the questions, I have NOT taken it apart yet and probably won't before sending it in so that Sal and the gang can take a look at it "as is". I'm honestly not exactly sure what it is that's causing the sticking (looks like rust to me, but I've been wrong before) and maybe it will clean off quickly with a quick disassemble, but it sounds like something worth at least looking at. All I know is that I used to be able to thumb the blade out a fraction of an inch and then snap it open the rest of the way with a flick of the wrist - sometimes even with just a strong flick - and now it most definitely requires two hands to pry it open. It's been exposed to a little sand here and there, but I always rinse any grit off after that kind of use, even if it's just with a splash of salt water (as counter intuitive as that seems - salt water seems better than nothing when it comes to sand and grit).
Sal - do I need to include anything with my knife when I send it back to you, like a note referencing all this? Do I send it to the same place I would for a sharpening? Thanks for the help!