Tritium Dial Turning "Tropical" (Cream) but Hands Aren't

[gmcjetpilot]

My 32 yr old (1991) Rolex Explorer II, has tritium dial and hands. As the original owner and only having it serviced once by Rolex I am sure it's all all original.

I can tell the dial markers are subtly turning cream. The hands are still white.

Reading once I recall this is normal, where dial turns first and hands stay white longer? Can't find the reference.

Can anyone enlighten be on this topic of Tritium Lum turning into