Single ultra high heart reading

When my apple watch 9 is on in background, walking or hike workout, I have been getting an odd out of sequence high heart rate. It is between 20 and 40bpm about what I am expecting returning to a normal reading on the next reading.

The watch is set up for the correct wrist, strap is not loose, no tattoos and contact not contaminated by dirt or sweat.

Interestingly, looking back at the readings the reading TWO back for the high reading has always been very slow to be added from watch to health on my phone. Normally between 40 and 60 minutes later!. It also shows sedentary context whereas all the rest show walking, background or workout.

The readings immediately before this spurious reading are normal, as are the readings after.

My heart has ben thoroughly checked out is is absolutely fine.

I wonder if some of you who have also experienced these high reading could look back at the reading you were getting before this odd one to see if you have the same issue.