These appear all over Ireland. Not quite as heavily used in most cases, but they're there.

http://www.megalithomania.com/show/image/1550/Currabeha.htm

http://www.megalithomania.com/show/image/2645/Annadorn.htm

(to show two that I can think of off the top of my head)

Here, they are usually interpreted as more modern marks made by people sharpening sickles and knives. The grooves are far too thin and shallow to be from stone axes.