maybe she's seeing what she can get away with... testing you. If she's all happy and waving when you put her down but cries when you walk away, I would think that she's just trying to get out of taking her nap. I would just walk away consistently every time. If she knows you're not coming back, maybe she'll start to go to sleep.

I have let all of my newbies cry it out from day 1. No hesitation, no re set, no going back in. And they all understand within a few days. One of mine still cries when I put her down, but only until I shut the door, then it magically stops. She's pretty stubborn by nature though, so I don't expect she will stop that any time soon.