The bushings are for the fork tubes to ride on, have nothing to do with sealing.
Okay let's eliminate some of the variables,
What kind of shape are the tubes in, nice and smooth, no scratches, nicks, etc.... Dust or dirt visible on the tops of the seals? It only takes a small nick or dirt to cause a leak.
Type of fork oil used, weight, conventional? Synthetic? Etc....
You can try a cleaning the seals with a handy little tool called "SEAL MATE"
http://sealmate.net/seal_mate_instructions.html
this method has worked for a lot people.
Link to original page on YouTube.
Worse case scenario, your replacing the seals.