domain mapping + bp + wp super cache

wp 3.0.3, bp 1.2.6, domain mapping 3.0.2, wp super cache 0.9.9.6.

just noticed a slightly strange thing with the above setup. everything working pretty good except when user1 has mapped their subblog.maindomain.com to say user1examplesite.com, other logged in users (e.g., user2, user3, and user4) do not show up as logged in in the buddypress admin bar at top when visiting user1examplesite.com.

now, i'm not sure if this is a super cache issue, but i have super cache set to "not cache pages for known users." basically, as i understand it, this serves dynamic pages to all logged in users.

indicative of the problem described above, user2-user4 are actually shown user1examplesite.com cached pages when logged in. they are not logged out or anything, as they are shown as logged in when going to other subblogs (not domain mapped).

HOWEVER, user1, when logged in, is shown the non-cached pages of user1examplesite.com!! ha.

soooo. have no idea...

any help is much appreciated.

btw, i also have supporter setup so only supporters can use domain mapping (in case that matters)