Hello S. - I have also had this happen to me recently with my 5 year old. As others have said, it seems like she is so involved in what she is doing that she can not tear herself away. I have an 18month old so I do not think is has anything to do with that since this is a problem we have only seen in the past month or two. I did take her to her pediatrician who did a urinalysis (normal)to ensure that there was not something else going on. We are currently working with a reward system (success about 50% of the time. I watch for the dance, but will get conflicting information from my daughter. I feel that she goes just a few drops to relieve the pressure, we are not going through 5 prs of undies, butit worries me just the same.
For example, last night we were at the bears game and she and I were standing in line for popcorn. She was jumping all over and I kept asking her if she needed to go (asked about 8-10 times in 15 min in line) repeatedly was told no and that she was dancing (there were some drummers that we could hear). After getting the popcorn, I asked and she said no and we returned to our seats. When in the car and getting pjs on for our trip home, she told me that she had had an accident when we were standing in line and that she did not want to get out of line to go. Please let me know if you find anything that works for you.
M.