This has been going on for at least a year in the Ilkley area, stones on Middleton Moor and Weston Moor had been marked when I was up there last summer.
Unlike the Willy Halls Wood stone where red gloss was slapped on the carvings and a few runes painted for good measure the new defacement seems to have a different agenda. Whatever they are using is a very thin fine dye (as the report states) which can't be felt if you rub your finger over it, it has also been applied very carefully which gave me the impression it had been done more with an air brush than a paint brush. Whereas Willy Halls Wood was mindless vandalism these new attacks seem to be done by somebody who thinks they are doing everybody a favour by highlighting the carvings or perhaps there's some kind of spiritual element involved in recreating the designs.
I'll dig out some pictures.

-Chris