ah, get your self a heart rate monitor, they are far more accurate, however.
My resting heart rate during sleep (I had a halter monitor for 24s a few months back) was 52, my waking at rest was 62 during the day (waking) under heavy duress it would reach 188, however in 1 minute 32 seconds my heart rate would drop from 188 to 120 after completion after what ever i was doing and over 4 to 8 minutes would fall to 72 again.
For me after heavy consultation with a cardiologist, getting an echo cardio gram, being put into an MRI machine to check my heart and valves and all manor of wonderful things, my heart rate is very acceptable and safe for my, my body and based off my physical size, the size and strength of my heart I wont experience any problems for a very very long time (baring anything unnatural)
you being physically smaller (but still being human heh) your heart rate should under normal circumstances be lower under heavy duress and your resting heart rate should be a little lower too, you should check after about 30 minutes of inactivity (lay down and watch a none scary, none emotional movie) and then check, the most accurate is the halter monitor, but probably very unnecessary for you.
What is really important though is you listen to your body, if you are experiencing any odd symptoms, such as, dizziness, shaking of extremities, vision problems, unrelated nausea, headaches, lethargy, troubles waking up, decreased appetite, increased urination that is seemingly unrelated to fluid intake or any problems specifically occurring during intense activity then you should go get checked out.