A stranger in my room

Last night I had an interesting talk with Austin at about 2 in the morning. He had come and crawled into bed with me. It has been a rough week. He really acted up Monday and I had to stop it, and he was punished. Then I went out to a SU party last night. So I think he was feeling a little lonely. SO in bed he is telling me he is scared. I ask him why. He says cause there is a stranger in my room. I ask him if he wants me to get up and check his room. He says not here at daycare. A light bulb in my mind lights up. So I find out today that A one of the girls that has only been working at daycare a little while left midway last week, and Friday a new person started. DS somehow missed the introduction on Friday, and so there was a stranger in his room. Monday was bad, yesterday not much better. I asked the lady to make sure she introduced herself to him, and I told him her name and that she worked there. Hopefully that helps the dropoffs. How to balance the danger of "strangers" with new employees at a daycare?
I am sleepy this morning, as not much sleep last night.