Has Your Toddler Suddenly Forgetten A Learned Skill or Reqressed in Motor Development?

We often see some regression in a learned behavior/skill with young children.  It sometimes happens when there is a big change in the family, like a new baby, Mommy going to work, or a move to a new house.  But other times it may be because your toddler is working/developing a new skill (somewhat subconsciously).  An example is when she is learning to use the potty, she may have trouble separating from you.  After the new skill is learned, the she then more easily leaves you and joins her play group. 
If you have read Dr. Brazelton, you may recognize this phenomna as a "touchpoint".  His book Touchpoints, Birth to 3, is one I recommend for every parent.  He writes in a style that we can understand and apply the information to our own situation.  What touchpoints has your child experienced?