Oh, I think I see what happened here. The IP space 4.0.0.0/8 was once upon a time owned by BBNPlanet. GTE (which later became Verizon) bought BBNPlanet, renamed it Genuity and sold it to Level 3. Apparently there's a stale database somewhere and the rdns for those IP's is still assigned to GTE/Verizon.
If I were a Verizon DNS admin, I could think of some fun games to play here.
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