simple answer -- no

If you are at the airport, ask another agent to call the gate and tell them you are on the way -- but if it takes more than 15 seconds, just go to the gate. As others have mentioned, the gate agent does not make the decision and you need to realize the potential negative impact to the other passengers.
While on the surface this might seem like a reasonable minor request but it can have other impications -- so while there is a chance of holding a flight, the bigger the plane, the less likley that is to happen.