Really?

I get stopped A LOT when I go to the grocery store with all six of my kids.  The thing is, my kids are excellent in the store.  It's not like they are screaming or running all over the place.  But we are like a miniature parade coming through, especially because I have to use two carts, so we attract a lot of attention.  I was in Walmart the Saturday before Mother's Day this past year (not the smartest of days to go, I know).  It seemed like there were a million people in there and half of them stopped me to talk.  They were all positive comments so it wasn't a big deal, but our shopping trip was getting quite ridiculously long.  I was about half-way through with my shopping when another lady stopped me.  "These aren't all yours, are they?" she asked me.  I smiled as I usually do when I get asked that question and answered proudly "yep, all mine!"  Her response caught me off guard and left me bewildered really.  She looked at me and said "I'm sorry."  I wasn't sure how to respond at first, but I quickly said "well I'm not.  We have a lot of fun together."  I am not the quickest thinker on my feet, and as I have often thought about that conversation, a million different responses come to me--things I wish I would have said and other things that I'm glad I didn't say because they would have been quite rude to her.  But it just baffles me how it was the day before Mother's Day and there I was having a great time with my kids and someone would "apologize" for the fact that they were all mine.  I'm not sorry at all.  None of my kids were a "mistake" and I chose to have each and every one of them when I did.  Okay, so the whole twins thing wasn't planned, but you know what I mean.  When and how many children you have is a very personal decision.  I hope I never find myself judging other people's decisions about the timing and number of children they have.  So what would you have said and have you had any experiences like this?