I am now getting this same problem despite everything working well last night.
As suggested, I only get the errors when I open the behaviors panel.
I am creating a site using Framework Themes and plugins.
The error is;
I am getting red exlimation marks next to;
Repeat Selection (which is in a plugin)
Repeat Region (which is in a different plugin)
Image Resizer (in the second plugin)
Show if not first page (in the second plugin)
show if not last page (in the second plugin)
Which make it look as though the issue is with Framework Builder.
Hope this helps