Maybe just a tad wet, if they are the 'vinca rosea'. I know they liked to be in loose well drained soil when transplanted. Also make sure they are not too crowded. The newer hybrids are more susceptible to wilt and rot disease, so if you just planted them yesterday, I might even re pot in dry soil where they can adjust.
It may be just transplant shock in which case they will recover quickly. But it may also be from excess fertilizer if the stems themselves are curling. Normally it's best to let transplants adjust first before fertilizing. I'd suggest you give them a couple of days in the cool shade to see if they recover, no additional fertilizer or water. You will know within 2-3 days if they will make it or need to be replaced.
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