[The Squatter of Amon Rûdh]

I expect that Gandalf has a particular affinity with fire, and that this was one of the reasons why Cirdan entrusted him with the custody of Narya. From the descriptions of Nenya and Vilya in the Silmarillion, we can see the influence of the Three on their surroundings, but to my mind the implication is always that certain inherent characteristics of the bearer alter the power and nature of the rings' effects.
This would explain why Gandalf was entrusted with the care of the Ring of Fire even though Saruman was the first of the Istari to arrive in Middle Earth (it's possible that Cirdan also saw something in the earlier arrival that disturbed him).

I meant to go into a little more detail, but time has caught me again.