Yes I also once experienced such a thing and after a few days everything returned to the normal mode again. If all of your links are gone when you use the link: command, that might mean something but a lot of ups and downs are reported by webmasters when they check their Google Webmaster Tools panel everyday to find surprises.
Some factors might also have roles to play in here like if you have been building too many links for one of your website too quickly or so many new content pages have been added to that specific domain which looks new or unprecedented to Google patterns.