Have you sprayed weed b gone or anything containing 2,4-D recently?

If so it *may* be herbicide drift.

Otherwise I really don't know. I have a couple asian pear trees whose leaves do that, but it is from a fungus that I have to treat each year. Not real familiar with common afflictions of sweet potato vines.

I've seen this before, but honestly don't know what it is. What I do know, when it happens to me, I cut off the affected leaves. That's usually the end of it. Robin

Looks like leaf stress disorder. That often happens to plants if some environmental condition changes in the extreme when the leaf is about to emerge - eg., suddenly too much or too little water or a big temperature swing from hot to cold or vice versa. Usually it only happens to those leaves that were about to emerge and assuming the conditions settle down, additional new leaves will be fine.

When you inspect the underside of the leaf carefully, pulling it apart even, is it free from any sign of insect activity?

i also had a few tiny leaves that had that look to them. my plants had a minor whitefly infestation. i don't know if that was the cause, but if you notice bugs on the undersides of the leaves, i can tell you what worked for me to get rid of them.