Well this is annoying. I last played on Sunday, mopped up a load of human enemies before making my way in a building to take on the next batch, entered said building, found a safe spot so I saved and quit. Loaded up the game today and I respawned outside right next to the group of enemies I had previously killed, who were now alive again.
So now not only have I got to kill them (all on alert) but the guys inside the building are now also mysteriously alerted to my presence. So are prowling around after me too. sigh.