I wasn't super surpised by the feat but I understand why some might raise an eyebrow over it. There are some possible factors I'd like to point out to explain the feat, ala, Marvel No-Prize style:
Silver Surfer's Power Cosmic does give him the ability to fight against chronal manipulation. More than that, Silver Surfer was dealing w/ temporal energies throughout the series and arguably became more acclimated to manipulating it.
For instance, Surfer absorbed the Time Gem's temporal energies Mephisto unleashed on Genis-Vell. Future Galactus ejected Surfer from time and space with a blast of temporal energy. Surfer ended up teleporting himself directly into Mephisto's realm.
Mephisto also might not be proficient with the Time Gem. Something which nearly every Time Gem bearer can be accused of: Gardener, Gamora, Maxam, etc. With the exception of, I guess, Rune??? Also, Thanos temporarily turned Runner into an infant. But that was by design to give the Collector his due.
Anyway, in conclusion, Silver Surfer resisted the Time Gem because Galan007 smells like butt. 👆