It may be thrips. Have you pulled the leaves apart to see if you can spot any tiny dark insects?
Renee

Here are some pictures of the leaves. Its not any bugs, the plant is very healthy.

As you can see in the last photo it appears to pass onto the children too.

Thanks for the visual- I had it all wrong in my mind. I have any number of iris that do that.
That's a healthy looking plant!
Renee

Oh so then this is common. I had hopes it was unusual. Oh well thanks for looking.