Last year one of my Annabelles had a stem with variegated leaves. It came up the same way this year. If I follow the main branch down, all the stems that come off of it are variegated except one. The rest of the shrub has the normal, solid leaves.
I've read about variegation due to virus, but have no experience with it. There is no change in the leaf texture. I like the variegation a lot, but if there's an issue with the health of the plant, I'll do what I need to do.
Sorry about the not-so-good picture - just took it with my phone.