Looks like it got cold enough to damage the leaves.

That is typical of frost damage. Sometimes frost damage will show up in a couple of plants and leave others a little ways away unscathed. It was probably a very light frost if it only damaged the top leaves. The fruit is still good though unless you get a killing frost

So I thought it looked like frost damage as well, but what I don't understand is how it could be frost damage. Please educate the ignorant here. It was quite warm that day (in the 80's I believe), and that night it only dropped down into the 50's. How did I end up with frost? There seems to be a lot I don't know about frost. I had thought it would need to be much closer to freezing for there to be a risk...?

It's called chilling damage. Doesn't go all the way down to 32F. Instead only 50 to 55F.

Anything I can do to mitigate it? Is it always an issue at 50 to 55F or only when there's been a large drop to get there?

Throw a blanket over sensitive plants; remove in AM.

You had what we call a patchy frost and I'll bet it was colder that night than you thought.

The air may be cold enough for frost but if the ground is warm enough the frost will just settle on the roof tops and not touch the ground. Sometimes certain things give off heat or there is a warmer spot that keeps frost from settling.

If you are up early and suspect there might have been frost you can water and wash the frost off before the sun hits it. It is the reaction of the sun on frozen plants that does the damage. You can set a sprinkler in the garden on a timer so it goes on just before sunrise, or you can do as jean suggested and cover them and remove it in the morning

Possibly "sudden wilt" but hard to say. Keep an eye on the plants. In the link below scroll down to "Sudden Wilt". Pictures (hard to see) are shown above the malady's name.

tj

Here is a link that might be useful: Sudden Wilt