The reading isn't cause for concern,no. Even if diabetic, it isn't within treatment range either. That's very remiss of her Doctor to be honest. It's only slightly above optimal (optimal being <120/80). Single readings are never diagnostic anyway. Her slight elevation could be explained by 'white coat syndrome'. Buy one of those BP monitors and for one week, record her BP 3 times daily. If it's consistently high then she may need to think about coming off the Pill. The Pill can cause high blood pressure
If she is overweight
, it could also be that. If she smokes she must stop and try to encourage her to reduce sodium in her diet. Exercise is always a must- this should all be done regardless.
Her reading isn't concerneing now, but as PJ correctly points out, it could be an indication for problems further down the line. Is she diabetic? Does she have any other heath problems?