Forum Moderators: open
Completely normal and expected behaviour. Your cache and listing may get updated if you get a visit from the freshbot before the next update. Google's cache is always 30-60 days behind. The freshbot was introduced to help alleviate this problem. Whether and how often it visits depends on your pages' page rank and on how often it is significantly updated. If freshbot visits and updates your listing/cache, but doesn't come back, your listing may again revert to the old cached copy.
See the Google Knowledgebase (link at top of Google News forum), and try a site search for "freshbot" and "everflux" here on WebmasterWorld to learn more about it.
HTH,
Jim