Stalker Mom - how do you know if your kid is "normal"?

Yesterday was the first day of school for my kids.  The very first day ever for the girl.  I've never seen  her so excited.  She hardly slept the night before; waking in the middle of the night singing, "school tomorrow, school tomorrow".  She walked right in...no tears.  I was so proud of her and left her beaming in a little chair, attempting to write her name for the very first time.  The boy and I walked across the street to his massive elementary school for his first day of 4th grade.  He was pale and shaky with nerves.  It's still hard for me to send him off on a first day.  Six years ago, I took him to his first day of preschool, just like I did yesterday with the girl.  My talkative, intelligent, silly boy turned into someone else when I took him to school.  He stared at the ceiling and never spoke.  He cried every morning and spent countless minutes in the bathroom, sick with nerves.  When his teachers wanted to talk to me about his inability to speak a couple months in, I was shocked!  It turns out, he never spoke even one word the entire time!  After much research and doctor visits, he was diagnosed with Selective Mutism (SM) and Obsessive Compulsive Disorder (OCD).  Selective what?  I know...no one's ever heard of it.  Someday I will tell you all about it, but I must move on to the stalker part of the story.  After walking the boy in to his homeroom, I headed back to my car, feeling a bit empty with no one in tow.  As I was getting into my car, I glanced at the school yard of the girl and found her class running around on the playground!  I ducked away quickly when she peered in my direction, slumping down in the driver's seat so as not to be seen...this was a covert operation, you see.  Any Mom knows you do not let a little one see you when stalking them at school!  As I peaked out the window, I saw a flurry of activity with preschoolers frolicking here and there, up and down, all around ~ all except my little one.  She was standing by her teacher, with her hands to her mouth...a very uncharacteristic stance for the girl.  My heart sank...memories of the boy and his struggles to socialize rushed to my mind and all I could think was, "Oh, no!  Not again!"  I tried to tell myself that this was her very first day of school - EVER- and the rest of them must have gone last year.  She just needs time, right?  OF COURSE!!!!  Her behavior is totally normal.  But, how do we know?  How do us Moms figure out if our kid's behavior is "normal" or if it's something more?  First of all, calm down and think for a minute.  Stop comparing your child to your friend's brilliant daughter, super out-going son, whatever!  Think about them in the context of who they are and what you know they can do!  Next, give it a little time.  Whatever it is you're worried about, wait a month and see if it changes or goes away.  Most of the time, it will!  And finally, trust your instincts.  You know your child better than anyone!  My instincts tell me my girl was just taking it all in and will eventually adjust to her new school life.  Only time will tell if this stalker Mom's instincts are reliable!  We shall see...