I just checked each quilt block and couldn't find any broken stitches. Thank you, Jesus!
) I guess the one long strip of fabric that I had sewn the sashing on was the only one that had any problems.
That leads me to believe that it was a barb on a needle that must have been clipping a stitch. Now that I have new needles, a clean machine, and new thread, we will see what happens.
If I continue to hear the popping sound, which made me think it was a dull needle or broken needle in the first place, i will let you know and get your thoughts on next steps.