What to do???

Monday night, I took the kids to dinner for a little first day of school celebration while Daddy was working.  We were sitting at our table working on tic- tac- toe when I felt someone staring.  I began to watch as the man from the table next to us just stared at Izzy- far too long.  He stared at her his entire dinner.  I caught his eye a few times and smiled but he just kept staring.  Now, I admit... I am a starer.  I prefer to call it people watching (it makes me feel better) but we all know it is really staring.  However, I know when I have been caught and I need to refocus on something else.  This guy... not so much.  I know Izzy is beautiful but I think he was trying to figure her out. 
As Izzy's mother, I of course, know she has DS but there are days when I don't think her features are as obvious.  When we are out and about, most people don't realize she has Down Syndrome plus this tid bit of information is not something I just throw out there during a first meeting.  Hi, this is Isabelle and she has Down Syndrome.  Down Syndrome, is of course, a part of our lives but we do live a very normal life- for us. 
I am still new to all of this and I am just not sure what to do in these type of situations.  But I did want to say something, not to be rude, but maybe ask him if he had any questions or open the door if he did want to say something- I don't know.  Maybe he was staring to figure her out or maybe he knows someone or has a loved one that has DS or a disability.  Or... maybe he thought I was crazy to have brought 3 kids to a semi nice restaurant all by myself.
I know I search for little girls/boys that have DS in our community but I have still not gone up to one of those Moms or Dads and said anything.  I simply stare.  Maybe one day I will feel comfortable to walk up to someone.  This is all a learning experience for me but I do know that Isabelle is beautiful and she knows how to make people smile.  If only she would have realized he was staring she probably would have waved and opened the door for conversation.  Maybe next time!