Ooo! I like it, and... I can actually see the mechanics of how it got to Earth... There's precedent in canon for the dragons at least to end up going someplace they haven't ever been, and through time, if their rider has an image that's sufficiently detailed to get them there. If the firelizard can do something similar with an image, all it would have needed was an image of where Grissom is, and a big enough fright to send it flitting between from Pern somewhere in the future to Earth where it is, and that effort would exhaust it.

*pauses for air, and to stop geeking out when she should be going to bed*

Anyway. Lovely story, and I kinda want to know what happens next...