I think I dropped a stitch

[knittoknit]

I am making a scarf of k2p2 pattern and then knitting the purls and purling the knits. I looked away from my scarf for a second and felt a loop or something go loose. I thought I put it back on and kept going but now that I am on the next row I see a bump sticking out of the scarf. Are there any inks for a demo of how to fix this? Thanks for any help or suggestions!