When I try to knit looser I notice a difference so I'd say that could definitely be part of it. I'm working overall on looser and more even stitches so I've got a one row blanket going that it won't matter so much if there are some looser or tighter stitches, I need the practice. I'm doing a pair of socks too. They're in stockinette and 2x2 rib, my DS won't complain if some of the stitches are a little wonky. I worked a cable bag and frogged it for the same reasons you've cited.
I should never overestimate my basic arithmetic skills.