After doing a little reading, I found someone who stated that accounts without a character above level 75 will not receive prizes that are mailed from the Grabbit. I was supposed to have received a Fly Mandragora, a Gold Rune Stone, and a White Rune Stone from the Grabbit on one of my other accounts, but I didn't have a character over level 75 on the account. This restriction wasn't posted anywhere on the Grabbit, or else I wouldn't have done it.
I've posted a support ticket, but it's gone almost 48 hours without being looked at. If any GMs happen to see this, could you direct someone to look at ticket #256309? I would really appreciate it.