Good news: I'm still around.
The scrubber I used with some Deep Creep definitely smoothed some gunk off the filler neck, and the silicone seal of the cap got cleaned up in very short order with a rag and a few drops of good ol' MMO. I thought that seal was SUPPOSED to be a beige/brown colour...not anymore. a qtip's worth of lube and I won't be worrying about an evap leak there anytime soon...
and I haven't driven much, but there definitely is a pedal feel difference: it seems I can get off the gas sooner when starting from a stop. probably had a wee little leak that the computer didn't think was important, and threw more fuel at to compensate