I would wager that that's a "one-off" sign meant to blend in with the neighborhood. As such, it could be of most any vintage, but probably early 1960's.
It's not unusual to see variations in signage or store design to fit neighborhoods or shopping centers. Williamsburg, Virginia is full of examples, as is the Richmond area and DC as well. For example the Safeway in the River Road SC in Richmond was built around 1960 and is extremely colonial in design and had signage that was gold on a green/black background - you can see pictures here:
http://mysite.verizon.net/d.mcgrann/. I also remember going on a field trip to Williamsburg in elementary school where we joked about the "Colonial Colonial Store" that was in the old Williamsburg Shopping Center, though I'm not sure that was that much "colonial" in design.
This particular sign seems to me to be something I would expect to see in NW DC, probably along Massachusetts Avenue somewhere near American University.