I regularly read this blog and I found this post interesting and potentially of interest here. I know there have been several posts on experiences with potty training...perhaps for some of us our abdl ness has roots in experiences like this one. The girl described seemed to react to a new sibling (true in my case) -- dad seemed to be quite graceful but everyone has their limits.
As a parent, I relate to my kid's diapers in a totally different way than my own (I had a ton of anxiety about this before they were born -- worried that the attraction would carry over -- it didn't in any form). I can imagine it being frustrating having gone through training and then seeing this kind of regression. I imagine that given my experience I will have a lot of empathy for my child in this eventuality.