Is there any browning or spots on the stems or vine?

I just went out and looked, and the stems and leaves are all perfect. There isn't even any leaf curling, which some of my other plants in containers have. There are several more fruits on the plant still though, and they're all exhibiting the same brown, mottled symptoms.

Could it be the beginning stages of TMV?

That's what it looks like. Other tomato fruit diseases are shown here.

I'm wondering whether it may have been the heat. I've seen tiny fruit (smaller than a dime) abort when the temperature soars... it looks rather like the epidermis got cooked or damaged, then cracked as the rest of the fruit kept growing. It would affect the most-exposed fruit, probably, though I've never seen quite that effect before.

TMV is unlikely without foliage symptoms of some kind, and affected fruit typically stop growing, which means they wouldn't have that cracked-scab effect. I'd take a wait-and-see approach. Be careful to touch or brush past these plants last, and wash your hands after handling them; watch for any mottling of the leaves, growth distortion, or further fruit symptoms which affect all of the fruit on the branch or plant. If two weeks pass without seeing any other oddities, I think you can chalk it up to unusual environmental conditions.

--Alison

I segregated it from the other plants yesterday evening, and will give the wait-and-see approach a try, thanks Alison. :) The plant really does look very good, but it hasn't been all that hot here, compared to as hot as it's been in other parts of the country. I'm hoping that it'll just be these first fruits and that everything else that comes in will be ok, but I've been really careful not to touch the plant and then touch anything else just in case. I should actually move it even farther away from its brothers and sisters, I think, so I'll go do that now.

Some (not all) of the new foliage is now starting to show some weird symptoms of a bit of brownness, but they're not showing that patchy chlorosis or curling up (aside from some leaf roll that I've given up trying to completely control). I'm so puzzled as to what this could be.

I'll try to get some photos of the leaves a bit later, and maybe some other ideas will pop up.

I know this post is really old. but did anyone figure this out?

My cherokee purple are doing the exact same thing! I'm stumped!

Let the plant soil dry between watering. I think you are keeping the roots wet for too long.