midcitybeth, when you say "I bought 25 in merchandise and 25 gift card and was credited miles for the full amount" do you mean the 15 miles/$ have actually shown up in your AA account, or just showing on the shopping mall site as a transaction pending posting?
If you actually got the miles, good on you, as the T&C clearly state that GC are not eligible:
Please note these terms & conditions: Not eligible on purchases made with coupon or discount codes that are not found on this site. Not eligible on gift cards, gift certificates or any other similar cash equivalents. Not eligible on purchases made through sub-domains such as aarp.walgreens.com, AARP discounts, pharmacy purchases or prescription drugs but photo orders picked up in-store are eligible. Not eligible on Prescription Savings Club. Any return, exchange or other adjustment made at a physical store location for an on-line purchase may result in your purchase being deemed ineligible for reward.