http://www.parktool.com/blog/repair-...osts-and-stems

this is what i was thinking of...from the second paragraph in the link above:

"When inserting an aluminum post into a carbon frame, it is important to apply a barrier between the two surfaces. This is also true when installing a carbon post into a steel or aluminum frame. A 'galvanic reaction' occurs between the two different materials and this acts to eventually bond the post to the frame. Use a light coating of grease, anti-seize, or other lubricant to create a barrier between the two surfaces."

i guess i was mistaken in the sense that carbon paste is more for friction (and maybe just for carbon on carbon??), but it seems like the important thing is to get something in there to prevent bonding.