Hello,
if your daughter is 4 or under, then its typical early childhood behavior (my own toddler has gone through phases of insisting I wear a firefighter had while making his breakfast). Just ride it out and hope that sometimes she will let you in on her reasons as to why this is so important.
If your daughter is older, thats fairly odd behavior, and I would need to know more about her age and if this is a pattern of behavior.
Best Wishes
Rebecca Resnik
Great idea, I've been having similar problems with a certain shirt that my daughter seems to absolutely love... Thanks for the advice.