Figuring out what to say

Sometimes, when I'm out with Cooper, especially if Brad's not with me, it's hard to figure out what to say about Cooper.  A couple of weekends ago, for example, we were with some friends at a park.  Brad was at work, so it was just me and the boys.  My friend saw someone she knew, someone I would probably never see again, but she introduced me and my kids to the guy.  I could tell he knew that something was up with Cooper, who at three was quietly sitting in a wagon: not normal three-year-old behavior.  But I just didn't want to get in to it.  It's just too much.  If he had asked, I would have explained, in the most minimal way, that he has special needs, but why offer it?  I mean, like I said, I'll most likely never see him again.  On the other hand, I felt kinda guilty about it.  Like I was somehow shorting Cooper by not explaining why he was sitting by himself over in the wagon.  He was in the shade, next to the picnic table where all of our stuff was.  But at that very second, I was chasing after my very mobile, very energetic one-year-old.  And Cooper didn't mind.  He loves to look up at the leaves on trees.  I think he likes the way light filters through them (I mean, who doesn't?).  But still, I felt somehow disloyal to him.  Like he wasn't being included properly.  Ugh.  I know in my head that all of this is rather ridiculous.  Cooper is fine.  There is no need to offer anyone an explanation for anything.  But for some unknown reason, it bothers my heart.  Blah.