Don't Delta and United have a reciprocal deal allowing CRC members to enjoy domestic RCC when flying United and vice-versa?
At
http://www.delta-air.com/prog_serv/c...ties/index.jsp you find "Enjoy access to all U.S. United Red Carpet Club lounges."
So, it may be easier in such cases to access the lounge with RCC memberships instead of CRC ones. Or next time just use the RCC (if available).
Not that you should be forced to use these options...