Im gonna take a wild stab at this and say that you slipped a stitch instead of knit it on the previous row.
looks like this VVV
and when you pull on the bar, does it pull on the stitches on your needle?
easy fix....turn your work where the knits are facing, put the slipped stitch on the left hand needle and put your right hand needle thro the stitch as if to knit, pick up the "bar" and pull it thro the stitch just like your making a knit stitch. pull the old off the needle and make sure the new is in correct oriantation. Turn work back over to where you were and continue.
You could do this proceedure while your on the purl side....its easier to explain for the knit side tho.
I hope thats what the prob is..
and I hope that helped?