Groomers put the dogs under a heater or dryer to keep them warm and to finish drying their fur after shampooing. Some groomers leave the dogs in there too long. Did that ever happen to yours?
Once my dog came home super thirsty and I had no idea why. It occurred to me later that they probably kept her in the dryer too long.
I haven't noticed that though, and my Dog is usually really thirsty and would want water every one hour.
I can't say I have ever noticed any dog I have had at groomers being under a heater for too long, to be honest. I guess it is something that can happen though, especially if the dog can be a little too fidgety when being groomed. As long as your dog is feeling okay after having a drink and it's not a regular occurrence then your dog should be fine.