If you are not planning to get glasses from them, it is unnecessary for them to measure your Pupillary Distance. The measurement of the Pupillary Distance is not a requirement to an eye exam. So only when you intend to order glasses from them can they measure your PD.
Actually the PD has nothing to do with eye exam and it is not required in the US or Canada either. The doctor would only measure it if you are going to buy glasses from them at the same time. You can aslo measure you PD by yourself at home with a ruler and a mirror.