It's difficult to make any comment when we don't know where you live, what you've done with the soil & water, how many hours of sunlight, and what the prevailing temperatures are.

I guess I need to put more stuff next to my name. lol. What's your guess by just looking at the picture?

One small portion of one leaf is not a problem.

What do you see that you think is a problem?

Also, the night-time hours are too cool for cukes unless they're protected and kept warm.

Yes. It's a little cold for them. Maybe I'm too eager to move them out.