I do this too!! Only in groups of 2's, and when it has an odd number of letters I have to keep going until I accept that one is in the middle. I have other OCD tendencies too, most of them related to sleeping:
-closet cant be open at all, even a little crack when I'm sleeping
-I need water by my bed at all times even if I'm not thirsty or it's hard to fall asleep
-same with putting on Chapstick and lotioning my hands before bed
I know there are more that I just can't place right now.
Sent from my "smart" phone, 'scuse crazy typos.