I had the same problem with my potted Lilies when they were overcrowded in the pot. Do your Lilies have enough room for roots?

Yes it is just one bulb in one pot (is that gallon size - those I recycled from other plants bought from Home Depot) and I planted it also deep like 6 inches.

Is that some kind of virus or disease?

I have seen leaves of plants do this when under "stress" (too much/too little water, sudden cold or heat, etc). They eventually grow out of it when the conditions stabilize. Otherwise, if the soil was not good, it could be some type of disease, although a common one like botrytis often manifests as lower leaves yellowing and browning out and continuing up the stem.