Hmm. I've run into a bit of strangeness with the offline mode; the launcher seems to want to go into offline mode fairly often, even though I don't have connectivity issues and should be able to access the minecraft servers without issues. Half the time, I can even decline to run in offline mode, restart the launcher, and get properly connected the second time around. Not sure why that is, but if offline mode is a new and somewhat buggy feature, that might explain things.