Rows of cup marks are very common in Ireland,
especialy the Wicklow stone circles and tombs.
They certainly appear on the top of some stones
although they are typically elongated cup marks or
short, deep grooves.

from a circle
http://www.megalithomania.com/Athgreany/image6.htm

from a tomb
http://www.megalithomania.com/ballyedmonduff/image5.htm

They do not seem to appear on standing stones in this format however.