[ConfusedGardener]

Are these anything to be worried about? Only a couple of Cassablancas have them where as the Rockets all seem fine.

[BabbyAnn]

I probably wouldn't be worried given the healthy state of the rest of the plant.  You could always nip off the offending leaves and dispose of them (don't compost) and avoid touching the other leaves in case it is a bacterial/fungal or viral infection.

[fatcat1955]

Looks like a viral disease called brown spot to me. A cousin of blight but not as damaging.

[ConfusedGardener]

Thanks for the replies. That's good to hear. I guess I'll just have to keep an eye on it. Not too much longer to go anyway.