Losing teeth question

[KrisM]

DS1 lost a tooth this morning. When I looked at his bottom teeth, he has 6 on his right and now 4 on his left. I think this is his 10th tooth lost so far, which seems to line up with what I think are adult teeth and baby teeth. I vaguely remember that he lost an extra on the bottom before the adult bottom came in, as he didn't have much room for teeth.

My question is, is it normal to be so uneven on losing teeth?