---not being able to find something I know is in my sewing room (usually scissors or seam ripper)
---chain piecing smaller pieces without pinning - and finding that every 2nd or 3rd one is off enough that I feel the need to rip the seam and re-sew.
---bobbin thread running out - yet I don't notice until I have sewn for some time after (and am excited that I got a section, or a long strip, done)
---probably my number 1 pet peeve right now - no matter how carefully I cut, press, piece - darn it all if some of my squares are slightly off. On my current quilt, this will be my first try at squaring up my blocks before assembling the top.