The way they are arranged "talks" virus to me.
Then, again, you'll never know by looking as you say.
If this is a valuable plant, then I would test it.
Purple pigmentation showing up as a result of high light usually appear as subtle or strong purple hue that cover the entire leaf (or in the back or near the tip or along the edge...) rather evenly or tiny (and not so tiny) circular marks.
Or at least those are the most common forms I have seen in cattleyas and phalaenopsis.