VegasJen, I'll be the odd one out. I don't know what caused that tube to split.
It sounds like you're doing reasonable things to avoid pinching the tube. But once a tube starts to blow, weird things can happen, as Peruano noted. While I won't say it can't happen, I've used tubes for a dozen years (patching as necessary), so I doubt the "old tube" idea. And there's no better match for a 23c tire than a 23c tube.
So what do you do now? If you've got plastic rim tape, replace it with the good stuff (Velox). Stuff a patch kit, a replacement and a spare CO2 cartridge in your pocket or seat bag.
And you know those folks on the tube patching thread who say they don't patch because they can get bulk tubes from cheap suppliers from the far east? Don't buy your new tubes from wherever they get theirs!