Hi and welcome back to the world of knitting.
Your tension may be a little uneven, but the stitches should even out when you wash the item. You can do that now - put the sts on some thread and just hand wash it and lay it flat to dry. If that doesn't seem to help, and you haven't been adding or reducing stitches (count them and see if it's the same number you started with) then if you can post a picture we might be able to see what's going on.
sue- knitting heretic