So I have a seven month old daughter and she's been sleeping pretty solidly through her nights since…

So I have a seven month old daughter and she's been sleeping pretty solidly through her nights since about 3 months old. Twice in the past week and a half she's had nights where she eats her last bottle and I put her down but as soon as she hits the crib she's screaming. She want's nothing to do with it. Tonight is one of those nights. The first time it happened I thought it was her teeth becuase she was biting down on my knuckle pretty hard and she didn't stop crying as soon as I picked her up so I gave her tempra and after about 5-10 minutes she was calm and I put her down. She slept through the night. But tonight every time I went in to pick her up she stopped crying and even smiled a little. When I look in the monitor shes making big screams for a bit and then stops dead in the middle and almost looks like she waiting to see if someone is gonna come into the room so I stopped going in. I'm keeping an eye on her but at what age did your babies start doing this whole "fucking with mommies emotions" thing? Sorry for the long post. TIA