my first broken bone experience

Oh, so my poor little guy broke his arm last night. He was, of course, climbing and jumping, but just happened to land the wrong way on his arm. He was climbing on the play kitchen set (shown below) and he was attempting to do a back flip off the top. Well, he didn't stick the landing and ended up going to the urgent care. Luckily Michael was coming home and was able to take him while I stayed home with the girls. He had several x-rays and indeed has a buckle fracture. We went to the Dr.'s office today and he was fitted for a cast. He chose green (his fave color) and he has been so marvelous about the whole experience. He has only complained about pain when it happened and when he woke up. He has been so tough, calm, and responsible about his broken little arm. He broke it just above the wrist and it will heal just fine in about 3 weeks.
On another note, his birthday is the Saturday and he is very confused about it. I had a b-day party for him w/his preschool friends a couple of weeks ago, then, they sang 'happy birthday' to him in primary. His concept of calender hasn't quite sunk in yet. He tells me emphatically, everyday this week, that TODAY is his birthday, and I tell him no it is Saturday, and he argues with me about it like he is so sure. I got into a very embarrassing argument about it with him yesterday...
he said, "mom, today is my birthday!"
me "no, it is sat. Nov. 8"
him, "no, mom, it is today and you said we were going to grandma's."
me, "no Reese, Saturday."
him, "TODAY!"
me (yelling now) "NO REESE, SATURDAY!!!"
and this continued for about 2 more minutes...it became comical to me b/c he has such a strong will. He will believe what he believes, even tho it is totally wrong and he refuses to believe his mother, is this a bad sign?