I would say it means nothing. What's important is your ranking in the SERPs. Has it changed? Users don't use the link: command to find your site. Google has already said that the link: command only shows a sampling of the backlinks for a site.
Dunno, my sites improves in the serps all the time, new links are build all the time (most of them naturally btw) but the 'official' Google BL dropped a lot, like 50%
A drop in Backlinks shown by Google means nothing. Google, by their own admission, only ever show a sample and the sample is not representative of anything. In fact, last time my backlinks displayed dropped, they went back up by x% from their initial count a few days later.