My 2.5-year-old daughter is a good educated child that hasn't many bad behaviors. Sometimes she turns out to be more the defensive type than the aggressive one, but all in normal frames.
When she wakes up (and cries) at night I come over and give her something to drink and calm her down. After 6 o'clock, once she's awake, I'm fetching her to our bed where she joins my wife and my other (half year old) daughter. This worked very well for us for a long time now, she cuddles me or my wife and sleeps another hour or two. She is also going very well with my other daughter.
But 3-4 weeks ago she started to keep crying when I wanted to fetch her in the morning and didn't want me to pick her up. She wanted to keep on crying and I wasn't able to calm her down. A few minutes later after the crying intensified, my wife came over and suddenly my daughter wanted to be picked up by her and was instantly calmed down on her arm.
This behavior has occurred since then seeming randomly about 1 or 2 times a week. No specific day, no specific crying or action the day before or anything special in the night.
My neighbors told me they got the same problem, but vice versa with the child wanting his father (they both fetch their child in the morning).
I don't want to know what to do against that behavior, I'm more interested in the roots of this problem and why only one of us can calm down my daughter in this cases when every time else both of us can calm her down easily. Why does she act that way only sometimes?