Leaf curling can come from so many things...too much moisture or too much nitrogen, aphids, it can also be from herbicide spray or the dreaded 'leaf curl virus'..check to see if you have purplish veins under your leaves for the virus.
Most times it's just damage from transplanting or the plant trying to conserve water..if so the plant will be fine. Even herbicide sprayed plants will usually make more leaves..
Seems like large staking tomato plants are more likely to have leaf curling.
As far as the cukes..it could be from the water on the leaves but also from a bacteria that alot of cucumber plants seem to end up with..you should water in early, early morning so your leaves have a chance to dry during the day.
Just keep an eye to see how it progresses, it could also be the starting of the dreaded Downy Mildew.