The new radar is a bit more sensitive and will indeed pick up cyclist or motorcycles gaining on the riders position.
I called and spoke with technical support because the same thing has been happening to me since I upgraded to the RTL510. Annoying as heck! And Garmin's response was, "Yeah they do that", even when I pointed out the old Varia design didn't pick up cyclists. Real good response, Garmin. And it's been two years since the last post. Wahoo Roam, here I come. jimg