Strange re-color after Text Box is dismissed

Following the tutorial at the 1 hour 14min mark where the NPC with Text Box is done.
Getting this strange color on the background after the Text Box is dismissed.
any ideas? See below link:
https://github.com/nroflmao/NesMakerHelp/issues/1

Nevermind, i found someone else reported this here:

http://nesmakers.com/viewtopic.php?f=23&t=617

i guess its a bug then

Not so much a bug, but the way NES Screen Data is handled.
The system can draw as small as 8x8 tiles, but palettes are handled in 16x16 chunks, and the attribute table is handled in 32x32 chunks. Fixing the attribute table would require more code, which is already limited in space.
Eventually I'd hope that they set up the Text Box mode to only allow you to follow the attribute table so people don't run into this bug, but for now the easiest solution is to expand or shrink the weird side by one block to align with the table.

Gotcha chronos, thanks so much for the explanation. That actually makes sense i will try it!