It's moisture in the air that has condensed but not had a chance to fall out. A little cloud chamber effect in the Fit. Somewhat like opening your cold-spot freezer on a humid day.

Mine did this too, before I had it fixed. It could be a symptom of the evaporator getting too cold. Or it could just be an extra humid day. By itself I don't think it indicates a problem.

 

We used to have one or two members that worked as Honda service writers (see the sticky thread for technical service bulletins and Recalls at the top of this forum) that gave us heads-up on TSBs. But no one in a while. It's not publicized. I don't doubt one exists for the A/C issue given the amount of chatter here about it.

I'd be willing to bet your problem is solved.

 

I just came up from Florida to Pennsylvania a week ago. My speeds were closer to 75 the entire trip, all interstate, keeping up with the left lane. My mileage was closer to 33 too, that is the negative. My first long trip with the 2013 Honda Fit and I was impressed when I did get to the hills. There are a few long hills as I came north from North Carolina on 77 to 81 in Virginia and then again on 70 as you come north in Pennsylvania plus additional hills up through the center of the state. I was pleased with the power and performance of the Honda Fit! I was able to continue up the steep hills without constant shifting, I think it stayed in "fourth". So perhaps keeping the speed up kept it more in the power band so it didn't have to keep shifting? Of course when I got to the two lane roads, my speed was 55 or maybe 58.
That said, I agree with the lack of kick when you want to pass someone on a two lane that is going 50. I want to kick in the afterburners!! But... I live in Florida, and with a lot of 4 lane and no serious hills, I am very, very happy with the car. 95% of what I need a car for at a great price with great quality and great mileage.
Oh, I do have tinted windows (film) and it is to Florida standards which is darker than allowed in Pennsylvania. I would recommend anyone interested to get it done, the price is not that great. I also picked up the XL rectangular window shields at WalMart that fit well for like $10 bucks and I use them when I leave the car for more than an hour. When in Florida traveling into the sun, the windshield is the greenhouse and it feels warm. Overall, the AC handles it, no freeze ups yet.
Thanks for the informative post of your round trip!

 

When I was on my road trip and having this problem I was turning the compressor on and off. One time, I was turning the compressor either on or off and just like you said steam or vapor came out. I'm in my 60s and I've never seen anything like that.