I have a GE Biax 42w PL-T that flashes brightly on startup followed by a pink glow accompanied by striations.

It slowly shifts to the 3500k it's supposed to be.

Reminds me of how a HID starts up.

The amalgam, designed to keep the mercury pressure at its optimum at the operating temperature reduces mercury pressure at all temperatures. Because operating temperature is designed to be rather high (for a fluorescent perspective), at room temperature it absorbs majority of the mercury back into it, this leads to too low mercury pressure for correct operation (instabilities in the discharge shape and its brightness). So the amalgam needs to warm up to the operating temperature to release the mercury and then the released mercury has to be distributed over the whole tube.

It is not just the really high temperature CFL's, even some T8's are suffering from similar effect, mainly when long time left unpowered at cold location. The mercury condenses on some metal parts and after power on it needs some time to get spread along the tube back.