I believe the customer service representative was mistaken.
The following is from the NGC website:
NGC utilizes numerous other designations that do not, however, constitute varieties. These include designations such as FH for Full Head, FT for Full Torch and FBL for Full Bell Lines. Likewise, the designations BN, RB and RD for Brown, Red-Brown and Red, respectively, are not varieties. NGC assigns a + to coins at the high end of their assigned grade, approaching the quality requirements for the next grade. The coveted star designation is utilized by NGC to identify coins that have exceptional eye appeal that distinguish them from other coins of the same technical grade. All of these are designations that NGC's graders look for in the normal course of grading. They are not classified as varieties, they do not require an additional fee, and they do not need to be submitted under VarietyPlus.