I see that all the time here, I believe it's from thrips. You won't see any insects if you pull apart the bud because they've usually gone onto the next life stage by time you see the damage. Shoot it's hard enough to see the adults most of the time.
On the ones here there's usually lots of those protrusions on the bud. I'll see if I spot any tomorrow and take a photo.
Of course it could just be a rare occurrence and have nothing to do with thrips. Sometimes the buds here won't have any other signs of thrips like the splotchy coloring on the blooms.
