My 3 year old is obsessed with ABCs...is this normal?

My 3 year old has been obsessed with Abcs for a year now. He plays with the same two ABC puzzle toys over and over again for hours. He sings it all day long and can even sing it backwards. Every where we go, he identifies letters on cars, billboards, wherever. Wondering if it's normal?On another note, he also has very specific ways of organizing everything and keeping everything clean. His toys are always in rainbow color order (I never taught him this?) And trains have to be a certain way... etc. If a chair is out of place or if my cat is sleeping anywhere he doesn't normally sleep, or a blanket is not folded in a certain way, my 3 year old has a complete screaming meltdown.Is this typical toddler behavior or should I look into getting him tested? via /r/Parenting http://ift.tt/2G2JYiw