As long as Prime has the correct credentials to add the device, SNMP, etc. you should be good to go. If you add the WLC to prime with R/W admin credentials, there is no problem, Prime is essentially a trusted administrator.
Some side notes, disable any default SNMP Communities, Users, and standardize on SNMPV3, as it's really the only secure SNMP out. Otherwise you have to secure the heck out of any management VLANs with SNMP traffic.
