As a psychic medium, I hear/see this all the time. It's no coincidence, but an intimate way for loved ones to communicate as Spirit and let us know they are around. They often show up at first, then again on special days ir in aime of crises. One of my clients found piles of pennies in crazy places--on a bedroom windowsill, in the middle of her garage. It was her dad getting in touch with a bit of flare.
Thanks for sharing your lovely story!