We know that Google will pull a snippet for a Meta description if your supplied description doesn’t have enough relevance to the searcher’s query. But, in this case they are pulling a direct snippet from your own content…. Not necessarily so for titles according to JohnMu who says this:
Google has known searchers do this for sometime…and they have preached the use of great and unique descriptions along the same line. Remember, your Meta description does not help you rank… but is rather a unique opportunity to elicit a click from searchers. This element however, if not appropriate for the query will be replaced by a snippet to better serve the searcher…. All good, no arguments here.