If I remember correctly, separation anxiety normally kicks in at around 6-8 months, and it could be that she was just having a bad afternoon. But it could be that your baby is developmentally ahead of the timetable. If you keep her secure with lots of contact while you are with her, and exude total confidence in her well-being as you leave her with someone, it shouldn't last too long. If she reaches for you as you leave, as if the world is going to end, don't you believe it, or she will too. Just wave bye-bye one more time, say "I love you, sweetie" (confindently, not longingly), and get out of there fast. I know lots of parents have success with the sneak-out approach, but I found that when I took a direct, confident approach to saying goodbye and leaving while they could see me, then they never had to look around and wonder and get anxious about whether I had left or not. They knew, and they could cry for a couple minutes and then get down to the business of finding something else to do. I felt like I was being honest with them, and they would almost always be happy until I returned.