Preschool and grown up

Caleb just started preschool. Tuesday was his first day of going without me. He came home and crazy me felt like he seemed sad. So I kept pestering about how his day was and if anything was wrong. He told me over and over he had fun. The conversation ended when I said "Your face just looked a little sad to me when you got home." His reply in a slightly exasperated tone was "Mommy, I wasn't sad. That's just the way my face be!"
The conversation reminded me a little of days when I was in high school and my mom would ask me the same thing. My reply probably wasn't so cute to her then but the same idea came across.
He's getting so old. He's so good at expressing himself and picks up on subtle conversations between Michael and I. We constantly have to watch what we say because later brings it up. Nathan on the other hand immediately says "What daddy/mommy" and "why" all the time.
A couple of weeks ago I was on the phone and Georgia asked me how I felt during my pregnancies. I responded with "Well, Caleb was really bad and Nathan was great." Later Caleb said "Mommy, I'm not really bad." How sad is that. Hopefully I didn't give him a complex. I'm glad his self esteem is good enough to say I'm not bad.
What an amazing boy. As much as he wears me out, he's great! I'm watching him change from a toddler to a kid right before my eyes.