I usually take 50mg of atenolol per night, but I may have taken another dose (making it 100 mg). I honestly do not remember if I had already taken my dose. Heart rate for me hovers around mid 80's to low 100s. There's been at least 90 minutes between doses, if I did take a dose.

Normal heart rate is 60 to 100 bpm. So you are in range.