Well Pressure Tank from 35 PSI to 65 and back every 7 minutes
You should be able to CHECK that there's no leak on the house side by simply shutting off the valve (that should be there, but might not be if your plumber was clueless, I suppose) between the pressure tank and the rest of the house.

If you do that and the behavior continues, yes, you have a problem on the well side - check valve not working, cracked pipe, something not as it should be, and you will need to check that. Depending on what type of pump you have and your well setup and personal mindset, that might be "call a well company" or it might not. If you are not comfortable opening the well and hauling pipes (with or without a pump attached, depending on your setup) up out of it, call the pros. 

If the behavior stops, you need to check the house side - water softeners are my "hidden leak of choice" because I used to have one that liked to stick open and run the well like crazy, but they are not the only possible choice.