Resting heart rate and vo2 max... im confused

lmsp95

So....I've been working out consistently for about 9 years now. High school and college track, and for the past year just running and lifting to stay in shape. I didn't start tracking my vo2 max or resting heart rate until about a year ago when I got a Garmin. Since leaving undergrad, my vo2 max has dropped almost 10%, which is kind of expected, because I am definitely not working out with the same intensity as before. However, my resting heart rate has also dropped as well, to 37 (whereas it used to be in the low 50s). I was wondering if anyone could offer insight as to what is happening here. Why is my resting heart rate falling given that i am in worse shape? Also, is it unhealthy to have a heart rate this low?