Hugs, Hugs, and more hugs! That is scary and awful! Is there anyone who commented on them, or has given you reason to think it would be them? Ugh. I don't know that I would leave necessarily, but I would be leary and watchful.
When my son attended preschool at a local church, one we were attending at the time, they were always looking for abuse signs. He decided to play Tarzan one day, and climbed furniture to reach the blind cord up at the top of the window, and grabbed ahold of it and jumped.. resulting in a tiny rope burn across part of his neck. The teacher and director marched him to the pastor's office wanting to call cps.. he laughed in their face. Luckily, he had enough brains to know that little boys (and girls) do these things.. and this was the same teacher who didn't understand why my son was always climbing out the playhouse window (a foot and a half off the ground), and trying to jump off the playscape... they KNEW he was an "adventurous" kid. They also freaked out because his favorite color was black (a sure sign of abuse, right?) So I said, "Did you ever ask him why his favorite color is black?" His answer: "Because black has all the colors of the rainbow in it, all mixed together." :D (sweet boy!)