Small Luzula species?

I've had this cute little clumping grass forever... bought from a vendor of alpines many years ago. It gets to 8" max in flower, and about the same around - a useful and rather attractive grass (IMO), small enough for the rock garden. It just occurred to me today, as I was photographing it, that I think it's a Luzula, from the hairy leaves and appearance of the flowers. Does anyone know which species it might be, or if not a Luzula, what it is? Many thanks in advance for clues to an old mystery.