My average HR is very low.

I am reasonably fit and been doing quite a bit of running and cycling since last year. I had a run with a local running club and some guys who were training for a marathon. I am not used to run with other people and it was actually pretty cool to talk during the session. One thing I noticed since I was going much slower than my normal marathon pace (7:40/miles) my HR would never come up more than 127bpm even if running for over 17 miles. Is that normal? I had to sprint at the end to get the HR a bit moving but even then it didn't go more than 150bpm https://imgur.com/3Aj8n