The day Ina was born, I worked all day and I was ticked off at my assistant. I thought she was being so smug ... I spent the day getting all the "must be done before the due date" things checked off my list, and (to me) it seemed she spent most of the day clucking around saying how good it was that I was getting this done, because "you never know" when the baby will come. I was ten days from my due date and thought she was acting like I was going into labor *that day* or something.
So Ina was born at 4:30 the next morning.
With SJ, I wasn't sure if I was in labor or not and called my sister to visit while I was putting away laundry (nested all day but I'd been nesting for over a month I suppose by then). It was my actual due date. My sister told me she didn't think I was in labor (she's had three and is an RN) -- then dh came into the house looking for me and yelled wondering where I was, and I bit his head off. My sister said, "Oh, yes, you're in labor."
And I was. SJ was born a couple hours later.
So .... I do think that there can be mood swings (or crabbiness) before labor. But it may not be imminently before labor, KWIM?
Incidentally, I apologized to my assistant for being so crabby the day before Ina was born, and she said she had no idea I'd felt that way, and certainly hadn't thought I was going to have Ina so soon either. So I was apparently also hyper-sensitive in a way that exaggerated things (she'd have told me if I'd hurt her feelings, and she's sensitive).