You would have to refer to the datasheet, as it will tell you exactly how long its rated for X temperature for its soldering profile.
There are a few ways it could cause problems, from flux leakage under the crystal (A little leakage can kill low power oscillators). to melting the base or some internal support inside the crystal,
You could have also had a dry joint with the pad under the crystal being heavily oxidised, I've seen weirder multiple times,