I too have the exact same problem. In fact, not only is my end site one big stew of excessive compression, but the whole Muse application isn't optimized for Retina. I use Illustrator, InDesign, AfterEffect, etc and they all look fine on the Retina MacBook, but the whole Muse application is pixelated.
Very disappointing to see Adobe progress so slowly to fix this issue.
I've attached a screenshot showing this problem. Note the difference between the system menu bar and the Muse toolbar.
