Excellent! I realize that there were no polymer elements in that Plunker, I was just trying to demonstrate that simply including platform.js on the page broke that angular directive. :)
Unfortunately, that was my sad attempt to reproduce my problem with the fewest lines possible, but I'm using 0.4.0, so I know that's not the actual solution to my issue. I'll try to make a simple Plunker that reproduces my problem. Not easy since my app has a lot of moving parts (ui-router, loading templates from templateCache, etc.), so it'll take me some effort to figure out which part is the real culprit. Maybe it's instructive that the plunker in 0.3.4 acts precisely how my project is acting with 0.4.0...
Thanks again for the sleuthing, and I hope we can get to the real cause.