The glyphosate is long gone. You just have to sit back and watchthem recover.

Oh, I hate thistle. And I have found that Roundup doesn't do all that much damage to thistles, either! Grrr. Can't help you with the azalea, I agree you just have to wait and see. I suppose you could prune off the new growth if it looks ugly to you.

When a stubborn weed such as Thistle, pokeweed, etc. grows and intertwines with an ornamental try the following. Cut the weed off almost at ground level and put three drops of Clorox on the freshly cut stem. Should solve the problem. Helpful on deeply rooted weeds.

Interesting. Is there any possibility the stunted growth is from a nutritional deficiency, and not the glysophate?

The following U. California, Davis web page appears to support your original conclusion of glyphosate affects:

http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7465.html

"Glyphosate damage may appear at bud break the following spring after a summer or fall application that contacts leaves or stems; symptoms include a proliferation of small, narrow shoots and leaves."

The following thread gives the links to scientific studies which I feel supports a model of glyohosate to soil, then release from a bonded state, and take-up by the roots in the spring by the affected plant:

http://forums.gardenweb.com/forums/load/weeds/msg081647415766.html?24

Here is a link that might be useful: U. C. Davis article