There is no st between the m1 stitch. You've just finished a regular stitch, if you stretch the needles apart a little you can see the strand of yarn between the R and L needles between sts. Pick up that st with the tip of the L needle and purl into it in such a way that it's twisted to close up the hole. Then just go on to the next regular st on the L needle.
sue- knitting heretic