With a sunburn you will have damage more over all the plant.
I would not worry bout it, right now. Get those girls outside and aclimated as quick as you can. I don't take over a few days in shade/sun then two three hours full sun with the sun/shade for a few days then they are ready to go full time. 7-8 days should do it.
Looks like whatever happened is on the lower leaves, right? She will prolly grow right out of it. Sometime stuff just happens. You got a healthy looking plant there.
Bugs is the battle outdoors. That does not look like bugs.