So I wake up after a 4 hour nap look at my WoW screen and see that my character has mailed his items... OR HAS HE?!?!?! So I check the recipient and I see no mail... but all the ore is gone.
Check with a vendor first to see if your toon vendored the items somehow. Then check GB to make sure you have the mail recipient name typed in correctly. Who knows, you may have just made some other toons day! What does your log say? Does the log say you gathered x number of nodes or was there perhaps an error and nothing was gathered? Who knows. Easiest thing is to check the simple things, if you cant find the issue, simply forget about it and begin again and keep an eye on it when your bags get full next to see what the toon does. Just my 2 cents.
Be sure you haven't mailed anyone else recently. I had a day or two where I had mailed something off to a friend, and they ended up getting all my ore for a day 'cause of one of my addons auto-filling their name in.