Changing priority from bug to wish as it seems that that it has no effect on the running system (see following code):

+   if (!found) {
+       cnt++;
+       WARN_ONCE(cnt > AUFS_PLINK_WARN,
+             "unexpectedly many pseudo links, %d\n", cnt);
+       au_plink_maint_block(sb);
+       err = whplink(h_dentry, inode, bindex, au_sbr(sb, bindex));
+   ) else ...

Possible solutions remove the warning, increase AUFS_PLINK_WARN or just ignore it ;0 

The reason and other workarounds for this message are described in http://osdir.com/ml/linux.file-systems.aufs.user/2008-
04/msg00010.html