I'm dealing with the same problem, although I think I was lucky enough to spot it before it got that bad (plus I keep my car covered most of the time.)

When I first noticed it I did pull up the front portion of the carpet as far back as I could (it's a single piece and I didn't remove it from the sides) and felt the metal behind it and the foam backing. Both were dry, so I proceeded to clear the drains, make a baffle to protect the AC inlet a bit more, etc. and after soaking up the water in the carpet I figured I was good. Is this still a safe assumption?

I assumed that since I didn't feel any dampness on the foam part and the metal seemed dry that the leak was new enough as to not be a problem. Plus, I had gotten the air filter replaced not one week prior, and the mechanic (to whom I've been going for well over a decade and whom I trust a great deal) didn't notice any water in that area -- which he most certainly would have, had it been leaking like it was when I caught it. A quick visual inspection of the blower assembly yielded some corrosion and debris, but it seems to work just fine and there's no electrical damage elsewhere AFAIK.

Based on the above, is it safe to assume that I dodged a bullet and caught the leak before it caused pooling in a harder-to-reach area?