When a resource is next to a city and you build on it, in the case of my current game an air shard, it gets added to your city's build queue as if it were another city improvement.  When a resource is not right next to your city and you build on it, it does not get added to the city's build queue.  

This has been reported before and we've never gotten clarification if its intentional or not.  The behavior seems kind of goofy.  I'm curious if it's intentional or if there are plans to make this more consistent (either both scenarios are added to the city's queue or neither are).  I can provide a save game if that would help.