When Maren went through this, it was right after we'd gone camping and she'd slept in the bed with us in the trailer. Since we've never coslept, this was a huge novelty for her, but as soon as we got home she went through massive SA when put in her bed for sleep. It was like she figured out that when she's in her own room, we're off doing something else. You just never know where their little minds are going!
As for Miss Hayden, she had no NWs last night and went down relatively easy tonight... she stood up as soon as I put her in her crib, started to cry, I said no, honey, it's bed time now, you need to lay down, and she did. Then I left the room and she's been quiet ever since. So not perfect yet, but WAY better. I don't know what triggered it, but she is talking a lot more now, saying words that are crystal clear where last week we might have been the only ones to understand her, so I guess it could be developmental too.