[TxMt] Strange ruby syntax coloring issue (b13)

I just updated to b13 (from b12) and svn up'ed the latest bundles.

When I open a myfile.rb file the syntax coloring is normal (same as in b12). If I then open a myfile.rhtml file the coloring is also normal (different than with .rb, but same as in b12). If I then switch back to the myfile.rb tab, the syntax coloring becomes, for lack of a better word, confused. Seems the background color remains the lighter color used for .rhtml file rather than switching back to the black color used for .rb. If I close and reopen myfile.rb, the colors are again correct.

I've removed all of my local ~/Library bundle files and restarted TM - same result.

If this is unclear I can probably manage to create a screenshot or two.