I’ve been knitting an earflap hat, following an extremely easy pattern (it’s stockinette for a bunch of rows, then decreases) on 3.5mm dpns. I got to the bind off and decided to do kitchener st on the sts (I didn’t want to turn on the computer to check what to do). When I finished, I saw that the hat was all folded: the grafting had pulled the knitting and tightened it. Once I tried it on, I saw that it was EXTREMELY big (if it didn’t have decreases it was sweater size). 
So I undid it and am beginning from scratch. This time, it looks too small. But I’ve decided that it’s very stretchy, so I’ll just go on and do a better BO.
This is what happens to me for adapting a pattern to smaller needles so quickly. The other time (while knitting a shawl), a similar thing occurred, and my shawl’s sizes didn’t follow at all the pattern’s. I now promise myself to get the exact gauge of what I’m knitting before doing anything.