Losing a domain?

How on earth can a registrar lose a domain?
I got this from a well-known ICANN registrar today:
The domain is in our system as a ‘lost name’. Please let me know which account you would like the domain pushed to and the registrant information that you would like on the domain.
So it was like Little Bo Peep losing her sheep??
How on earth can you “lose” a domain?