power was fluctuating during a storm. The entire street was doing it. I didn't call the POCO obviously but then I noticed when the power would come back on during this fluctuating, the pole mount transformer would buzz. Would it be normal for a transformer to buzz when the power is restored since its likely under load?

 

Not a continual buzz. You are never wrong to call the POCO if you think there may be a problem. If the buzz continues, a fuse link will disconnect at the transformer. Since it didn't it should be ok.

 

Probably because it was under a heavy load as when the power comes back on so does everyone's refrigerator and AC or heater
and motors require quite a bit of amperage to start
so that x the whole neighborhood

 

All magnetic transformers hum or buzz, but you normally cannot hear it when the transfomer is mounted high up on a pole outside. That being said, I remember many years ago that a friend of mine mentioned that the transformer on a pole outside his home had been buzzing quite loudly for several days following a storm. I stopped by that afternoon and he was right, it was much louder than any pole transformer I had ever seen...or heard. I checked his voltage and found it reading 144/288 volts. The 120 volt kitchen clock was making a loud humming noise too. The next door neighbor's refrigerator had gone out a day earlier. He called the power company with that information and within 1 hour there was a crew on site changing the transformer.