Sticky heart rate after exercise.

https://trumelabs.com/blog/normal-heart-rate-recovery-chart/
When I was not fibrillating in earlier years, my HR would remain elevated depending on the intensity and/or the duration of my running session. Normally it would only stay elevated for perhaps 10-20 minutes, but with hydration and being calm and at rest it would soon be below 60 BPM. Nowadays, with an older heart, and with it somewhat disordered, it can spike higher during stair climbing and routine walking, and it might remain high for an hour or more, say 75 BPM. Note that 75 BPM is high for me because my new, older, HR is typically 63 BPM.
I don't feel that several hours with elevated HR after golf is right. I could see if it it was frisbee golf, and you wee running between greens, but not otherwise. I would ask a cardiologist to have an examination.
I did mention hydration. Poor/neglectful hydration can cause a spiked HR.

The speed with which your heart returns to your normal resting heart rate after exercise is called Cardio Recovery. You may want to research more detailed information, and talk to your doctor about any concerns.

I was diagnosed with paroxysmal Afib this past Tuesday after a night in the ER. Cardioversion didn't work, but I went into normal sinus about seven hours later. On Wednesday I decide to not let Afib, mitral valve prolapse and a mildly dilated aorta stop my running at least. I went for a 2.9mile run, slowly, and my HR got to 143. Toward the end it spiked to 176, but I stopped and walked a mile back to the car. It went down to 164 during that time. I got home and chilled where my HR dropped to the low 90's and stayed their the rest of the afternoon and evening. I do/did a lot of heavy lifting and intense cardio. So, 90's was showing probably a bit of dehydration and some over exertion given I hadn't run in three weeks. The important part is it dropped from 170's/60's to the 90's fairly quickly. Yours was during a more mild form of exercise and your HR would be considered normal for every day activities. If you are saying that when you are walking and talking you are in the 50's that is really good. I don't even do that and my resting HR is 45 bpm. It could be some dehydration, I've experienced that running in high heat, but I would wonder if you hadn't had enough fluids for a normal day versus a heavy workout. You indicate that it is a regular thing. If you exercise regularly then I would say it is an issue as you should have cardio recovery after ceasing exercise. You sound like you exercise regularly and know your HR when you are just relaxing. It wouldn't hurt to see the Doc and find out whether there is an underlying cause. I should have seen a doctor earlier this year as I think I've had this at least since February, but I thought it was just a "phase."