Your sore throat may or may not be related to the drug but there have been reports in some Toprol studies of hypersensitivity reactions such as "fever combined with aching and sore throat". However, it's not a common side effect.
I'm not sure it fever always accompanies the sore throat in these reports but with or without fever, if the soreness persists, definitely see your doctor.
Nothing & everything is a common side-effect with B/P meds. I have learned that through time. There are so many side-effect & many are listed as rare. I don't buy it. My big toe hurts every few months for no reason.... I believe it is the meds.