What's up with this? On typing?

Okay. Since highschool I've noticed that sometimes when I type I may press the wrond key by spelling out the word in my mind correctly and thinking that I'm typing it correctly but I end up jumbling the order of spelling. And this happens only when I type pretty much. In high school I was good at vocabulary and the top speller in my grade. So what's up with the typos? And seems like the older I get, the worse it gets?