Indeed, it's definitely a patch of melting snow. It looks like the final remnants of a snow bank thawing out on the sidewalk. In the 2 exterior shots, there are no leaves on the ground and the trees are green with no signs of turning colour. This is a strong indication for spring season (and as a Long Islander, I'm sure you're familiar with that).
As Crack said, we discussed it back in the Chronology thread...albeit, 3 and half years ago.