Originally Posted by feline fanatic

It is entirely possible. I believe (not 100% positive) that one of the designations in machine needle sizes is the size of the eye. That is why different thread weights require/recommend different size needles. So if you changed needle size without changing thread I can see where it could effect your top tension and you would need to make a minor adjustment. Here is a handy guide from Superior threads for needle sizes and thread types that may help in the future,
http://www.superiorthreads.com/media...HOME_12-11.pdf