Can a mini split unit be 5lbs low on refrigerant without a leak?

Im in the process of buying a home with a mini split unit and during the inspection it was blowing cold air. The homeowner called an hvac company out and they said it was 5lbs low on refrigerant so they filled it up and put dye in it and came back 7 days later and said the unit was fine and wasnt leaking. My question is how is a unit thats only 2 years old be out of refrigerant and not leaking? Can this be possible or should I be alarmed