If you happen to hear random shots close by, you might want to investigate, because the traders could have gotten caught up in your "activation zone". Or the other option is to immediately fast travel away. Unless you don't worry much about the traders.
Then again, it could be talon company versus a couple of radscorpions...
On topic, falling protectron or just bodies falling from the sky. One thing that throws me off, in Megaton, I come out of a building and Paladin Hoss appears out of nowhere and runs out the gate....
I have also had Paladin Hoss invade my privacy after a good night's sleep in my Megaton house. It's creey enough with Dogmeat and Charon peeking in while I'm sleeping, I don't need ol' Hoss doing the same.
Of course, now that he's dead due to Raider bullets and a nearby exploding car(it happened before I even got to the location!) I don't have to worry about it anymore. The nameless Brotherhood Paladin that accompanied him on his original mission to save the Initiative still likes being creepy though.
I have heard the explosions in the distance numerous times(never bullets, but occasionally laser fire). I never investigate(maybe I should!). I wonder if that is what happened to Doc Hoff? One day he just stopped showing up, but I have yet to find his corpse lying in the wasteland(along with his bodyguard that didn't do their job). I have come across a pile of corpes that you wouldn't expect to find together in the middle of nowhere. There was a pile with a dead Robobrain, Radscorpion, and Mole Rat in it!
I once came across a dead Outcast Patrol(near the road blockade with the tent where they were going to "clean up" the radiation pool which turned out to be a small puddle) and started looking around in fear(if something could kill three of them, it MUST be dangerous, right?)! It turned out to be a Giant Radscorpion! That's it?!?