A pink hue is typical of some good sapphire, sometimes they even call it "pink sapphire" (e.g. ofrei).
But it should be barely noticeable, only when looking at the sapphire from very skewed angle. That is why you can hardly notice it when the crystal is mounted on the watch.
It is also more noticeable on domed crystals like those of PAMs than on flat crystals like the SSD.
Being your DSN crystal domed, and as it was not yet mounted on the watch, you were simply in the best possible condition to notice it.
That hue will stay unmodified by single AR. Unsure about double AR.
Personally, I prefer to leave the old gasket in place when replacing a crystal. The old gasket already got shaped by the old crystal, it makes fitting the new crystal easier.