i went into the Repconn HQ on my way to Vegas. All the droids were friendly, both outside and inside.
I lockpicked a door to the right of the entrance way and a Facial Recognition droid comes up to me and says im not allowed etc. I win the Speech challenge and it says im ok as long as i dont go up to the second floor.

So i think to myself, thats ok im not taking on plasma equipped Gutsys yet, ill just look around and take the guided tour.
I take the tour, and not two seconds into it, before the tour droid even gets through the first doorway a Maintenance Droid comes up to me and says im trespassing and all hell breaks loose with sentry bots appearing and everything. :/

wtf?

bugged or what?

I do remember one of them asking me to leave because visiting hours are between 10:00am and 5pm.

So I left, did a wait, and went back in.

Check what time you are in. I went in there and the bots told me that the regular hours are from 10am-5pm. After that you are considered trespassing. Same thing happened to me in the first try

its midday in my game just before i saved before entering the building.
so its not the time of day doing it.

It may have been when you unlocked the door, one of the security droids from past it came wandering to your location.