If someone stole it for the copper, I would suppose they didn't know copper wire for antennas, copperweld, is mostly steel.
And was one or more of the trees in the front, near the street? Or near a utility pole?
If it was near a street, you local municipality might have done it. In my neighborhood the city periodically sends a bunch of workers around with a cherry picker, trimming trees. Or if it was near a utility, one of their workers might have done it.