Look like a multiplication problem to me, send me the exr if you like dave@simplymaya.com I'll try the same thing in nuke.
By default maya will premult the passes so.... I can't help with AE I stopped usines in ages ago i'd probably just end up confusing the issue. I can test your output image in nuke though if you want
Dave
From a readers' Q and A column in TV GUIDE: "If we get involved in a nuclear war, would the electromagnetic pulses from exploding bombs damage my videotapes?"