Yep, that was me. How would you have dealt with it?

Try to pretend like it's not there. People will see who did it if you just ignore it and score the tile with the line accordingly, but when you try to fix it like that, they think you did it, or something.. That and it generally looks better as just one white line than multiple white lines or with a tile a shade lighter. You did good enough though. At least your whole tile isn't a shade lighter. :)

I believe Slothy said somewhere that it was possible to 'seed' a quilt with more that one starting tile, but that he didn't usually do so. Maybe he changed his mind?

It was because someone uploaded a tile to the left of this one that wasn't going with the theme, so I deleted it... however, the tile spaces created by that tile existing for a few seconds still existed. It's generally a good idea to stay away from the no border tiles when you see that the first tile is already turned in because of that. There area few unexpected things that happen. Sure, you might think, oh wow COOL! I'm going to get one with no border! but it's just a bad idea.