Half-Life 3 Trolling?

A photo posted on Twitter by Uber Entertainment's Chandana Ekanayake shows a t-shirt with a Half-Life 3 logo, saying: "All I'm saying is I saw this at a local game developer event worn by a Valve employee." Whether this is significant, or just trolling is not clear yet. The two hash tags he uses for this are #HalfLife3 and #ValveTrolling. Thanks Computer and Video Games.