Adults Judging Children's Books Pt 1 of 10 Million (I'm sure)

I set off alarms all the time.  It's reached a point where my friends actually refuse to walk into stores with me so they're not subjected to the awkward stares and random questioning that comes from any employee who cares enough about his job to actually do it. 

So today when I went to the library to pick up the million books I had on hold for school, the alarm naturally went off as I departed with my bags of books.  The security guard of course went through all my books and when she reached the newest Caldecott winner, A Sick Day for Amos McGee, she looked at me like I was crazy.   Seriously, what is the big deal about an adult checking out picture, children's or young adult books?  

What if I had a kid or a younger relative and was merely checking out the book so I could enrich said child with the charming tale of a man who is home sick and taken care of by his animal pals?   Granted that's not the case, I checked it out for my own professional development, but still there's really no call for immediate judgment of a 23 year old checking out a picture book.