This could only happen if the arteries were seriously constricting when the heart relaxes between beats but relax again when the heart pumps. So, impossible.
This is in NO WAY possible. It makes no difference what machine is used or who uses it. The blood pressure reading measures the pressure in the vessels at two times different times.
The top number, which is ALWAYS the higher of the two numbers, measures the pressure in the arteries when the heart beats (when the heart muscle contracts).
The bottom number, which is ALWAYS the lower of the two numbers, measures the pressure in the arteries between heartbeats (when the heart muscle is resting between beats and refilling with blood).
When you listen with a stethescope to take a BP, the cuff is inflated until you can't hear the blood rushing through the artery anymore (it sounds like the heart beating). You slowly release the pressure in the cuff. When you hear the heartbeat again it is marked as the systolic reading. When the sound decreases or goes away, you mark that as the diastolic reading.
You can see why it just isn't possible to have greater pressure when the heart is resting than when it is pumping. It would be like saying you feel more pressure on your hand when you rest it on top my hand than you do when I grasp your hand to shake it.
Unfortunately, I don't even have a guess at what the doctor might have actually said to your mother or meant by it. You may need to clarify with the office.
Mary