I recently upgraded my watch to a heart rate model. I've also gotten back to running a bit more seriously- I was just running 3-4 miles a few days a week (easy) but am now training for an upcoming half.
I've noticed that my heart rate is unusually high on my easy/recovery days, sometimes even higher than on a long run or tempo run. For example, average during a long run yesterday (9 miles at 8:28 avg page) was 136. Today, I did an easy run (2.76 miles at 9:39 pace) and average HR was 147 (but jumped all the way up to 170).
When I see the HR going high, I have tried slowing to as slow as I can run and it still doesn't seem to go down unless I actually walk.
I'm a 38-year-old male in good shape.