Mine's anywhere between 39 & 44 BPM depending on how stressed I am, when I last ate, when I last rode, how hard I last rode, yadda, yadda.
The other day it was 52 as I was walking my hybrid out of the garage to go for a ride.
I'm 59 years old and doubt that I'm that damn fit. I have orders to get an EKG to see if there could be something wrong, but I've been under the weather the past few days and haven't done much of anything, so I plan to go early next week.