I had heard about this bug and never experienced it until the latest play through.

At first I thought it might have been triggered by a certain Caravan card but then I realized the script usually takes a second or two to fire.

Here's what I did..

EDE loaded down with loot...enter Primm Casino..hostility.
EDE with nothing in inventory...enter Primm Casino...nothing. ( Stood around for 30 minutes RLT )
Start transferring items to EDE in Casino...hostility.

Tested 3x each...
Rebooted OS..

And I know I put stolen items in his inventory...but I don't remember what exactly what it is was though.

I don't have time to try each item...but it seems logical that a glitch is allowing the NPCs to see EDE as a criminal caught in the act or something. Thus triggering the hostility script.

It's also random.. I've had this happen a few times and reloaded save games and gone back into the same areas and nothing happened.

once in primm vicky and vance, once in the airport with the ncr (might be a normal thing coz the ncr chick said "halt" or something like that) and once in the repcomm (rocket launching mission) top area where you meet with the religious dewds that wanna go for a rocket trip.

Reload game and each time nothing happens next time.. I wasn't touching ed-e's inventory either. this is a known bug. I suspect it's some kind of weird faction issue where each npc is doing checks to see if they like you or somthing. (or ed-e dosn't like them?)

I'm having issues with named NCR attacking E-DE on sight. Getting annoying enough I'm thinking of just dropping it. Kinda svcks, since I usually use E-DE to carry all the extra crafting junk I pick up.