Curling leaves – overwatering?

Over the past week I have noticed the leaves on my plants (Money Makers and Sweet Million F1) have curled, and do not unfold. After a lot of reading I think this may be due to overwatering after repotting. They received a large soak and then the sun/warmth disappeared for a week (in London). Could this be the case or is there another reason I should be looking into? These will be planted into their final growing position in about 10 days once they’ve finished hardening off. Any help appreciated!