https://watchers.news/2016/03/18/asteroid-2016-ef195-detected-4-days-after-very-close-fly-by/
This may have been the one I was thinking of. 50 meters in size, .08 lunar distance(!!!), detected four days AFTER it passed by. That one that skimmed over Russia a few years ago was estimated at 25 meters in size.
Trying to find out about damage from a 50 meter object:
“The smaller an asteroid, the more numerous they are, is the general rule of thumb for our solar system. According to the best estimates, objects 3 meters across impact the Earth and deliver about 2 kilotons of TNT of energy. Objects 100 meters across collide with the Earth every few hundred years and deliver about 2 Megatons of TNT equivalent. A 1 kilometer-sized object impacts the Earth every million years or so and delivers about 100,000 Megatons of TNT.
Now, the good news is that the Earth’s atmosphere shields us from objects that are initially below about 100 meters in size because they break-up and evaporate before reaching the ground. Still, the famous Tunguska Event in 1908 was a 50 meter stony meteor which evaporated about 20 kilometers above the Earth, and still flattened trees in a 30 kilometer area. Its yield was about 10 Megatons of TNT, and the frequency tables predict that such strikes should happen every 100 years or so. The next one could happen any day between now and 200 years from now!”