If you are still making that square, just decrease--loop over hook, insert hook in 1st stitch, make a loop and pull it through the stitch; make a loop and pull it through 2 loops on the hook. Now make a loop on the hook and put the hook through the 2nd stitch. Draw up a loop, pull it through the stitch, and then proceed to make another loop and pull it through the first 2 loops on the hook. Then make another loop and pull it through all the loops on the hook. 2 stitches are now 1.

Unfortunately it is several rows back. At this point you'd have to know it was there so not going to mess with it. I will have to be more careful next time.
Thanks for the help Sheliajoyce :-)