I'd guess that the "cup of coffee" is the clue to what your son was feeling. The "cup of coffee" I'd think mean that he was telling you that he was aware he sounded emotionally flat. There are a lot of reasons a person feels emotionally flat. You being his mother it's probable he presumes it's okay to speak as he feels within reason.
That birthday present sounds absolutely spot on by the way!
Is there such a thing as delicious ready meals?
How do you acknowledge Easter.