As indicated in the post above, the knowledge of which brand drive was shipped 2 weeks ago, last week or even yesterday would basically have no bearing on the brand you might get in one ordered today.
Apple has been selling approximately 25,000 computers per day, 7 days a week. The brand hard drive you get will be the one they were able to get for the best price or was actually in stock regardless of price at the time you order.
If you have a preference, you should upgrade the drive yourself.