I noticed the same thing on the Kenmore I recently got - it's straight stitch only but my stitches looked slanty. I put a ruler against them and they're actually straight, it's the thread that's got a bit of a twist going and creating an optical illusion. I'm still sewing with one of the wooden spools of thread it came with; I think maybe if I try some thinner thread (like Aurifil) that might be minimized. I haven't tried flipping the spool yet, either - I was thinking maybe it's got the twist of the thread going the wrong way.