Triangular shaped "bubble"?

HeiHei29er Triangular shaped "bubble"? For my last two bakes, I've noticed an odd cavity on the outer edge of my loaves.  And now seeing it back to back, I think I've seen it in some of my other loaves too.  It has to be a shaping error with that triangular shape, but I can't figure out what I'm doing that would cause it.  It's on the outer edge, so has to be either how I finish rolling my oblong or how I'm putting some tension in the dough after shaping. Any ideas?