The one catch with my phone being rooted is that it always ends up in fastboot when it boots. A simple
I have a working su/Superuser.apk, but I can't seem to fix the bootloader dilemma.
As Jhal said, you can't "fix" your bootloader, it's locked since you're on the newest OTA and it can't be unlocked. With that being said, your phone is not booting into fastboot because you're rooted. It's booting into FB because you tried to flash something that didn't work. What other things have you done or attempted to do, besides rooting? This will help us help you, the info you provided is pretty vague.
I in no way implied I was AVOIDING unlocking due to the desire to stay on OTA's - just that I had no reason to pursue unlocking. This is the first android device I've had that ended up with a sunset where you couldn't unlock it at pretty much any point, so i never had a fear of taking the OTA and losing something in the process. If i had expected that, I certainly would have unlocked prior to 9.30.1 being installed. I honestly have yet to figure out why they don't release a program that would allow unlocking the devices - I'm not sure the manufacture's fear of unlocked bootloaders and root, as any program they release would be loaded with disclaimers - and frankly, it would allow easy restorations to ANY firmware version by service staff at verizon/at&t.