For a child's sweater, I think I'd just change needles, too. I seriously doubt that having the yoke a bit tighter is going to affect the fit of the sweater. I'd call it a personal design feature and move on.
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo!! --Hedgehog
IngridKH on Ravelry