I have recently discovered that this will also happen if you take cuttings from a mother plant that is too old. I usually rotate out my mothers, but in the case of one strain, the mother was over 10 months old. Every single clone I took from that plant when it was old did that. Sent from the grow room using my fingers.
It's from stress but it should pop out of it. I prefer taking clones in flower and the stress does that but they always turn around just fine.