I think sometimes we're so worried that other people will pick up on our mistakes and not mention them, just thinking to themselves that we are clueless and a bad quilter, or something, so we feel like if we point the mistakes out preemptively, they won't think that of us or something.
Recently I had a "humility block" of my own. Didn't notice it until I was done, binding on, label on, everything. I had to practically bite my tongue to keep from pointing it out to the recipient and everyone else. Maybe she noticed, maybe she didn't. No one has mentioned it.