The ladies have given some great advice. I completely understand the nerves leaving your precious bubba to someone else. My kids have been going to the same centre for over 3 years now and I'm extremely comfortable with the staff and centre but I still do surprise drop ins, stay for a while during drop off/picks ups occassionally, call the centre whenever I want to ask about the kids, question/talk to the staff about what my kids did during the day - I ask questions specific to my kids not just general ones like did he sleep, I talk to the director about anything I want.
I sometimes wonder if they roll their eyes at the sight of me wondering if I'm going to question them again, LOL!!!
If I'm uncomfortable about something I've seen/heard/been told by the kids I talk to the staff about it. There have been a small handful of occassions this has happened.
Trust your gut feelings more than anything.
Good luck.