it is okay for boys to be dirty

SJ and Bob were outside playing with a friend.  They were playing very nicely.  They were having running races in the driveway and riding their bikes.  When Bob and the friend went to see if another neighbor boy was home, SJ continued to ride his bike.  He must have rode through a big puddle.  There was mud all over the back of his bike, his shorts and his shirt.  When he realized that his clothes were dirty, he immediately started demanding that I wash them.  I told him that I wouldn't since if was around 7:00 p.m.  I told him he could change or keep them on.  I told him that it was okay if he was dirty.  He just kept crying and then came in from playing.  I hate that this extremely typical boyness of being dirty will totally halt SJ.  He ended up never going back outside.  When I went to check on him, he was in the playroom playing Wii in his underwear.  I know I can't be the only parent of a child with PDD that experiences this, but I feel sad for him that he sometimes just can't get past something this simple.  He missed out on another 90 minutes of playtime because he thought he had to be in clean clothes.  Maybe this is my fault for always changing them as soon as they spilled anything on them as babies and toddlers.  I hope I am not the cause of this compulsive behavior.  I will have many opportunities to work on this behavior if the rains keep coming.