Congrats on the circular knitting! That's a great technique to have.
Take a look and see if the hole is caused by an accidental yarn over. It'll look like a new column of sts starts above the hole. In that case, you can work over on the current row to the column of sts, drop the current stitch off the needle and let it run down to the yarn over and then continue knitting. Pulling on either side of the extra yarn will help that yarn work itself into the knit fabric. Amy shows how to correct a mistake
or a twisted stitch here although a twisted stitch doesn't usually give you a hole.