If by lettuce leaves you mean a frozen look, no that's not spring sickness. With spring sickness the fans are stunted and/or bend sideways and have "saw-tooth" ragged edges and holes in the leaves like in your pics - I don't remember now, did I think some of your previous pictures looked a bit like spring sickness?
No, no treatment that has been proven because we don't know for sure what causes it. Bulb mites may be involved but the damage occurred most likely before the leaves even appeared above the soil. We don't know whether bulb mites cause some, all or none of the damage for sure but the damage is typical of what they do to other plants, and they've consistently been apprehended at the scene of the crime in spring sickness. I've seen similar damage on tulips in the presence of bulb mites too.
Most of the time the plants will recover on their own and can still flower. In some cases there may be what I presume to be a secondary infection and the fan can rot but looking at yours I don't think that will happen in this case. You could try giving them some liquid fertilizer, that may help them grow out of it. Some people cut off the affected fans but that's just to remove the ugliness.
Edit: I would also say that if those leaves were frozen at some time those holes could be some kind of physiological damage from freezing causing uneven growth in those areas. We know full scale spring sickness isn't caused by freezing after fans emerge but there could be more than one cause of certain symptoms. It's also possible that a daylily might get frozen and already have been going to get spring sickness, doesn't necessarily mean they are related.
