Glad it's running, it may have been a variety of stuff. Don't ride the bike on Reserve unless you need to - especially if the screen on the petcock hasn't been cleaned - if you drain the tank completely, you can suck sludge straight to the carb, which will mean you need to partially disassemble and spray it out with carb cleaner.

But yeah, if the ceramic was cracked slightly, the plug could've been bad and you wouldn't know. Also, on some plugs, the tips unscrew - if it was coming loose slightly it might've been making bad connection. Sometimes if you're running the bike and turn the petcock past off, you'll get a little bubble in the fuel line and the bowl won't fill. Happened to me, a sharp knock on the side of the float bowl with the handle of a screwdriver helped!