Clone came in mail looks like reveg?

Give it time and she will get back to normal in a few more nodes... looked after correctly that is...

Some plants are sensitive and being in a dark box for a couple days but could trigger it to produce flower hormones. Or another option could be that the vendor already did the reveg and this is the plant after its started vegetative growth again which will still sometimes produce single leafed leaves here and there. To me the plant looks fine at the moment and doesnt look like its revegging very intensely if it is. a solution or precaution you could do, is to change your lights to 24 hrs on or 20/4 for a couple of weeks until its showing just vegetative growth and then go back to normal 18/6. some commercial places run their clones at this lighting so the dark box and then 18/6 at your place could also confuse them a bit. all in all i think the plants fine and it will straighten itself out no matter whats going on 🤙

Stress can have this effect too. As long as it doesn't branch like crazy, you can assume it was not a re-vege. All you can do is wait patiently to see the growth pattern. IF it's normal, it's not a revege. You'll be fine within a few growth nodes the leaves will be back to normal when treated well. Just get it healthy and it'll probably be fine. Can't do anything about a re-vege but wait it out, anyway. Sometimes leaves will do this just from LST.

it needs some magnesium. Also never heard of free clones with seeds. that's a neat thing. kinda makes the seeds useless lol Keep it going under 18/6 and it will reveg. or switch to 12/12 and bloom it out. just give it some feed.

I am giving a new answer after thinking about this a bit more: It could have been from a re-vegged plant as it does look like it has some unique characteristics. If you know the strain you can look up other grows and compare to see if it has similar growth. If your plant is showing unique genetic expressions that could be good or bad, probably won't know unless you grow it. To be safe, I would watch to make sure it doesn't turn out to be a hermaphrodite as it could self-pollinate or pollinate others. Growing a re-vegged plant is no issue, I had good results with mine, just keep the plant in 16+ hours of light for veg and it will be fine. I would grow it, always fun to see something unique!

Revegged maybe, although that would be weird IMO for a clone with a seed order from a vendor. Maybe just a bad frame chosen for the cutting, stress response, her natural shape, or maybe whorled?