this happens to me more often than i'd like. :roll:
you have nooooooo idea how much i wish i didn't know the solution. :lol:
if the skimpy seam is because the pieces weren't lined up correctly, then it's definitely time to pick out the wonky spots, realign and restitch. otherwise, your patches might not lay properly when it's time for quilting.
if it's because there wasn't enough fabric in that spot for the two pieces to line up properly, then restitching will also throw your blocks out of shape. so ... time for Plan B:
-treat the skimpy parts with a fray blocking product; once that's dry ...
-treat that section with a fabric glue that is washable and that will dry clear and not shiny. make sure to treat it from the back.
by double-treating the trouble spots, you shouldn't have to worry about future fraying or unexpected "parting of the ways".