When mounting an nfs4 share on a RHEL 6.1 instance with the "context=" option in order to allow a confined service to use it, the option is ignored and the nfs_t context is applied instead of the one set with "context=":

"""
[daniel@swrepo var]$ cat /etc/redhat-release 
Red Hat Enterprise Linux Server release 6.1 (Santiago)

[daniel@swrepo var]$ mount -v | grep ISO
storage000:/swrepo000/ISO on /mnt/ISO type nfs4 (rw,context="system_u:object_r:httpd_sys_content_t:s0",addr=XXX.XXX.XXX.XXX,clientaddr=XXX.XXX.XXX.XXX)

[daniel@swrepo var]$ ls -ldZ /mnt/ISO/
drwxr-xr-x. root root system_u:object_r:nfs_t:s0       /mnt/ISO/
"""

Mount correctly reports the context option, however the actual context set is different.