Equipment artifact or a real cardiac concern? If you're feeling a symptom, I would talk to a Doc
I do not see those drops on GoldenCheetah. I use a Garmin Strap and a 1030.
I get premature ventricular contractions and sinus pauses. My PVCs go away once I get into zone 2. It is like my carbs need rejetted. I do not see dips on my HR on the Garmin or GC.