I agree with Bakatare, she's stretching. Just to be on the safe side I would also put something to help support the seedling in case it keeps stretching. If it does it could flop over, bend at the stem, and that could cause you more trouble then you want. Tooth pick should do with a very loose twist tie around the middle of the stem. Once the stem thickens up and can support the top of the plant this can be removed.Yep, sure is.