I put a dahlia bulb in a pot a couple of weeks ago and it has been doing wonderful, but today I noticed that some of the leaves are curling. Should I be alarmed?

I have another one that had curled and was black. I pinched those leaves off and it seems to be doing better. I'm new to growing dahlia's and putting bulbs in the ground. It is so much fun and I hope it all works out. I have sent a picture so you might be able to tell me if I have a problem. I don't see any bugs.