The AGM-114 Hellfire only weighs about 100 pounds.. cant possibly create a blast felt that was noticed at that distance... or maybe they just heard it.
Actually, it can. Case in point- I live approx 10Ks from the live fire impact area of Fort Hood. When conditions are right, I can feel the windows shake on my home from hellfires impacting during live fire exercises. Also, the hellfires used may have been either the AGM 114M Blast Fragmentation or AGM 114N Thermobaric missile. I suspect it might have been the latter since those are currently being used primarily on buildings with devastating effect. The shock wave to explosive weight ratio on that one is quite large.