Goyo,
You're correct that they have been holding the earnings calls in the afternoon lately.However a A.M. call is not without precedence.They held them at 9 A.M. in April,August, and October of 2010.It probably doesn't mean anything.
http://seekingalpha.com/article/233332-mannkind-ceo-discusses-q3-2010-results-earnings-call-transcript?find=AM&all=false