No thats a new one on me, I have ncr troops spawn with me when fast travelling on occasion, but that can be a blessing in disguise somtimes.
The randomly spawning NPCs is usually a bug that comes with ED-E.
More often than not, and especially at Helios I, I get huge clumps of NPCs spawning with me when I open the door.
I think it has something to do with the companion string, but unlike everyone else on these forums, I'm not a programmer, so I'm not certain.
But overall, this is a fairly common bug.