Apparently. I walk my dog every night around 10:00 pm or so. I live on a corner lot, and tonight the first thing I noticed was "YBF" Spelled out in corn starch on the corner of the sidewalk, with a corresponding splash of corn starch on one of my trees. Continuing down the street toward the local lake revealed splashes at regular intervals.
It rained a bit this evening, so they must have run around 9:00 for the corn starch to be dry.
This is the second time I've walked through a hash. A couple years ago while living in Burke I found myself in the middle of a hash while walking through Pohick Stream Valley Park in daylight on a weekend. The hare passed me, and a few minutes later the first hounds arrived.
It's all pretty harmless, though I do recall reading about a panicked response to the corn starch piles in another city that led to a hazmat team being dispatched. When the hashers realized what was happening, one of them tried to tell the police it wasn't a terrorist attack and was threatened with arrest. I believe no charges were filed or they were dropped.