CBS News’ Mark Knoller probably knows more about the nuances of “Senate humor” than we do, and Sen. John McCain will probably take his colleague Lindsey Graham’s tweet in good fun. Still, with McCain visiting rebel leaders today in the very dangerous country of Syria, not everyone was in a laughing mood. Too soon?

Update: Though Graham’s joke didn’t fly with the majority of Twitter followers, Knoller’s giving him the benefit of the doubt.