I have a few Trillium Grandiflorum that are showing leaf symptoms that look to me like they could be from a virus infection, or maybe soil insufficiency.
The plants were purchased several years ago. Right now they are in part shade, sandy soil, they are only maybe 5 inches tall, much shorter than expected, and there are several trilliums a few feet away that don't show any shortness or problems. The mottling is more pronounced in person than with the picture. It mainly sows up as lighter green mottling on the leafs.

The main concern is just to be sure that it is not a virus that could infect my other trilliums.

PlantMatt, Could it be possible they need a little fertlizer? We have clay soil and ours are in pure shade here. I see the leaves are not as full as ours are. Ours is a huge clump.

It could be a result of poor oil, but the other nearby trilliums, different species, look alright.

I don't see any sign of viral infection.

What I do see is a slight nutritional deficiency: it could be caused by lack of nutrients, the rhizome having expended more energy than usual upon Spring growth or soggy soil chocking the root system and thus slowing down nutrient uptake.

Nothing to worry about in short.