There was a BC maintenance undergoing at the US data center during which publishing via Muse wasn't possible. In future, if you are not able to publish sites via Muse to BC, please refer to the following System Status page for Business Catalyst that gives you instant updates - http://status.businesscatalyst.com/. You can follow our Twitter page as well - https://twitter.com/bc_obnw.
Thanks,
Vinayak