It came down today
To test out what is happening after the sky high heart rate yesterday, I tried something different today. Put in a warm up mile first. And then put in a faster than normal for me 5K run. After that, another one mile to cool down. The 5K was in 26 mins 40 seconds (at my normal pace, it would take closer to 30 minutes). It was nice and cool 63 degrees.
The heart rate readings today was closer to what I would expect. Highest was 183. It is still higher than what I would think (170 is what I was thinking it would be). But I was also monitoring my lungs. At no point did I feel I was struggling to take in enough oxygen. I will have to monitor a few more days to see if the heart rate is unreasonably high.