Okay, started feeling better today (had what ever crud was going around for the last two days, stayed home from work but didn't want to do any sewing), and I got back in my sewing room.
I checked my triangles more closely, and noticed that some are off just a nudge enough so that when I sew with an accurate 1/4 inch seam allowance, they wouldn't make 360 degrees around, so therefore, would never lay flat.
So my conclusion is, if I want my hexes to be flat, I need to be more careful when cutting my triangles.
I need to make sure my fabric or my ruler doesn't shift when cutting, or I need to mark my seam line, even if it wouldn't be exactly 1/4 inch.
OR, I need to stop being OCD about it when making these quilts, as no one would probably even be able to see if the centers don't line up exactly, and once the top is quilted, probably wouldn't be able to tell that they weren't flat.
On my next OBW, I think I will starch the fabric, and see if that helps keep it from shifting, and keeps the strips lined up when cutting. And I think I will try the Creative Grids 60 degree ruler, or get those things you can put on your own rulers to keep them from shifting, and see if that helps as well.
Thank you, every one, for all your suggestions. Once I get the top together, I will post a picture of it. Not sure how long it will take me to actually finish the quilt, so won't keep you waiting THAT long. LOL
Diane, who is getting off the computer, and heading back into the sewing room.