I fell 3 times on my first day with clipless(I too use SPD), all happened after already stopped, one foot unclipped, then somehow forgetting the other foot is still clipped in and bike leaned that way, and boom! to the ground I go.

now I think those falls were good/beneficial - because they completely removed the fear of falling for me. You sorta come down on your side, on the knee and shoulder, so nothing serious/bonebreaking, it's more of a embarrassment/ego damage than physical damage.