Don't expect the shop to be open on Sundays until after Labor Day weekend. Although, there will be exceptions: rainy days, for example, are not necessarily covered under the summer Sundays exclusionary rule. It might be a good idea to call first if you're planning a visit. Just to be sure.
So please, if you like to read at the beach while being buried in sand or stared at by strangers, stop in on any one of the other six days of the week that Ada is open.