Looks like a little touch of frost burn, maybe? Did the weather get cold again after the plant popped up? Even one night of frost could do that sort of damage to tender new leaves.
Also the unscorched leaves look like chlorosis might be starting, too. The compost will help with that but very slowly. More of a long-term fix, and you'll need to keep adding it, maybe a shovel or two each month until you've balanced the pH of the soil.
For a quicker fix, I'd go for a half-strength liquid fert with some iron in the trace minerals. Do that maybe every second week until you see normal (uniform darker green) leaves.
