stranger anxiety at age 22 months and 4?????

Ok....so all of my kids went through the usual stranger anxiety thing at around 5 or 6 months then it stayed on and off until they hit about 3.....welll my little Jackson has done it all backwards....I kind of felt bad because when he should have hit the stranger anxiety stage, he was perfectly fine to go to ANYONE!!! It scared me, because he seriously would just go to anyone!!! His first day in the nursery was actually a couple of weeks before the "official" 18 month age where they can finally hit the toys and snacks during the 2 hour block at church....he just walked right in sat down and played the entire time!!! That lasted for about 3 weeks....then something just hit.....he missed mommy!!!!! I was shocked...it was cry, cry and cry.....until the pushover mommy came in to get him! I finally resorted to having valerie take him in...He knows when I hand him over to Valerie what is going to happen....the waterworks start, and guilty mom walks away....usually all it takes is for the bubbles to come out and he's fine the rest of the time.....Not so today!!! I was making my usual rounds checking all the classes, and I hear a blood curdling scream in the nursery.....one that I recognized immediately....it was Jackson.....pawing at the door like he was in a locked cage!!! We (Holland was with me) went in and you would have thought that we had just saved his day!!! The look of relief on his face made my hear melt. Did I mention that Holland hasn't wanted to go into her class lately either????? So I had 2 little ones by my side until Holland decided she wanted to go to her class. In the past I would have been irritated that they weren't staying in their class....not so now....I think it's because I know these 2 are my last and I know how fast they grow up and then don't want to be with mom...I'm holding on to the "moments" I"m blessed with to cherish with these 2 valient spirits before they could care less if mom were around!!! :)