I have a flight SMF to MSP. I booked it a few weeks ago in main cabin and got the complimentary comfort plus upgrade right away. I called today to apply a RUC and get into 1st (web site showed available) and the agent was adamant that since I bought main cabin under the new system I was already upgraded one class (to comfort) and couldn't use an RUC. Is she right or is this HUCA scenario?

Web site FAQs say:

• Flights with First Class: If you purchase Main Cabin or Comfort+, when you apply your Upgrade Certificate, you will be upgraded to First Class upon request.