Puppy Rate being charged for an adult dog?

For some reason my puppy rate for house sitting is $5 lower than my regular rate. I did not realize this and am going to change it however, that won't help this situation currently. When I did a meet and greet with this dog 2 months ago, he was a puppy. It's an active stay now but he has been a year old since before the stay started. His owner paid immediately after the meet and greet so she only paid the puppy rate. Is this correct? Would the age not be based on how old he is during the stay?