Can you unroll them or are they sewn closed. if sew then you have leaf rollers, if you can please post picks.
Pattie

Would overcrowding in the pot cause this problem.

No.

Is it possible they're overwatered?

Possible but very unlikely. Do the pots dry out quickly which would indicate a healthy root system? If so, you should put the pots in saucers full of water so that you don't have to water as often. If not, tap a root ball out of a pot and examine the roots for rot.

Did you fertilize? I suspect a potassium deficiency.

tropicanna with leaf roll problem
the leaves on this plant tend to roll up really tight when the sun is down (towards sunset), and unroll (never fully unfurls) with bright sunlight

{{gwi:537142}}

this australia has slightly less tightly rolled up leaves
{{gwi:537143}}

in contrast, the bengal tiger and florence vaughan leaves remain fully open at all times

by contrast, this tropicanna does not have the leaf roll problem--same watering, feeding, sun
{{gwi:537145}}

All came from Home Depot looking neglected--after reviving them, after a couple of weeks, I fed them a couple of times with water soluble miracle grow for bloomers (2 gallon watercan, 2tbs fert. among all). I keep them very well watered in high 90s and low 100s temps in zone 9. sometimes 2X daily if the soil dries out.