1.5.5 Update connecting to a huge pile of random IP addresses?

[PearTree]

I've been running SDV on MacOS X for quite a while. I use Little Snitch to monitor outgoing connections, and all of a sudden with the 1.5.5 update the game tries to connect to 70+ random IP addresses at startup on UDP ports ranging between 27015 and 27068. I'm running it through Steam and those ports are used by Valve for various matchmaking/streaming purposes, apparently. I'm not doing multiplayer or streaming, and it definitely didn't try to make all of these connections with 1.5.4. Any idea what gives?