Thanks for writing your query to us.
Pulse rate of 140/min is a significant finding needs to be evaluated. Any form of exertion or anxiety
can give rise to such high pulse rate. Since you had visited the doctor also & EKG was normal that indicates it was a transient episode which lasted for some time & then reverted back to normal. I would advise you to visit a cardiologist who will evaluate you in detail. Holter monitoring a heart rate can also document the episode of rapid heart rate
& also record EKG during the episode. Based on the EKG we can come to a conclusion that whether rise in heart rate is physiological (anxiety, exertion) or pathological ( due to disease of heart).
Wish you good health.