So, I hadn't heard from the Sherwin-Williams guys in quite some time, so I picked up the phone and called them. I got some "who struck John" that they had reached out to me several times (I never got one call), and that when they didn't hear from me, they returned the tint to their factory. I asked them what number they had on file, and he said they couldn't find it. Needless to say, I'm not going to pursue this any further with them. Probably just as well, as I'm still a few weeks away from being able to start painting.
Doing a quick internet search, I discovered there is a PPG paint supplier literally around the corner from my office, which has received excellent reviews. I'll go give them a try.