No you don't have hypotension. At the age of 55 I've had a bp around 110/70 for years, and that's while living a pretty sedentary lifestyle. If your ECG is normal, then your lowish heart rate is the result of being fit.
and I agree a target of 180 is both ludicrous and dangerous.
Here's the UK CAA guidelines for exercise ECGs:
http://www.caa.co.uk/docs/49/20030312BruceProtocol.pdf The Bruce protocol is explained in the British Medical Journal at
ABC of clinical electrocardiography: Exercise tolerance testing
You'll see in the BMJ article that the target heart rate is described as
Maximum predicted heart rate
* By convention, the maximum predicted heart rate is calculated as 220 (210 for women) minus the patient's age
* A satisfactory heart rate response is achieved on reaching 85% of the maximum predicted heart rate
* Attainment of maximum heart rate is a good prognostic sign
so you need to achieve (220 - 61) * 0.85, which I reckon is 135 bpm
TV
(a paediatrician, but I do know a bit about the other end of the scale)