Terrifying encounter between Andale and Factory

Like the title says, I was in between Andale and the Nuka Cola Factory filled with Raiders around midnight in-game time. I was sneaking away from the Raiders when I saw a glowing thing on the ground, and thought it was a mine I could pick up.
I went over to it and turns out it was an Alien Powercell, and a few more were to the right of it. I stepped closer to the cells when I heard a loud crash, not an explosion, a crashing sound louder than anything I've heard elsewhere in-game. I figured it was a Raider with a missile launcher, and pressed up against the canyon wall so nothing would sneak up behind me, when I saw even MORE alien powercells to the right. I picked those up, and turned back towards the factory to see if a Raider was chasing me, and standing there were 3 or 4 ALIENS!! They looked like the one at the crash site, but living!
I panicked and didn't have time to see what color their radar markers were; I threw my controller and turned off my system before anything else could happen.

Was this just a terrifying glitch?? I checked the wikia page for the locations of Alien Powercells, and they're not supposed to be found near Andale and the Nuka Cola factory!

I'm not making up a creepy pasta; this just happened, and I am terrified!!

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"This is good... Isn't it?"