What's going on???

It's been a strange few days in the Ng house. The last two nights, Abigail has woken up crying, crying which was on the verge of screaming. But, do you know what's weird: she didn't really wake up either time. Last night, Carey and I were putting away some clean clothes before going to bed, and Abby just started screeching. We ran into her room, and I picked her up. She fidgeted a bit, so I rocked her for a few minutes, but she never really woke up, so I laid her back in her crib. For a good 45 minutes, she kinda sobbed in her sleep. (You know how, after you have a really heavy crying fit, your body is wracked with sobs for a few minutes until you get back to normal? Well, that's what it sounded like.) It was strange because she never really cried, so the fact that she was sobbing was strange. She seemed to be fine, in no distress, and Carey and I couldn't find anything in our baby books that might explain this. So, we set the alarm to wake us up at 2:00 am, and Carey went in to check on her. She was fine. I got up at 4:00 and looked in on her, and she was sleeping soundly. When I got up to get ready for work at 5:30 am, I checked on her again, and she was sleeping like an angel, all cuddled up with her blankie.

So... Carey and I are at a loss. At first, we thought she might be experiencing teething pain, but she's fine during the day and, after each brief episode the last two nights, she's been fine the rest of the night. (We'd expect teething pain to be much more constant.) Any of you folks out there with kids experience anything like this with your little ones?