Newgistics has me worried

My husband and I upgraded our phones 2 weeks ago yesterday online. We both opted for iPhone 7's. When he opened his, I decided that I would like a bigger phone, like the Android I am used to using. I called AT&T and they suggested I take the phone to the nearest AT&T Corporate store (1.5 hours away) to exchange. I said that was fine and made plans with my husband for the trip down on Saturday. Thankfully, the Thursday before the trip (one week after upgrading),I called that store to make sure they could handle the exchange, and they said that even though the iPhone was unopened, they would have to charge me $35 restocking fee, and they didn't have the Plus model in stock. They said the best way to exchange would be through the mail. I followed the return instructions to a T - including taking photocopies of my packing slip and return label. I dropped the box off inside of the local USPS and got a receipt. The box made it to Grand Rapids MI and then was handed off to the "Returns Agent" (Newgistics). I have been obsessively tracking the device for the last 8 days on the Newgistics tracking website (http://www.tracking.smartlabel.com/), however the status of my box has not changed from In Transit to an Unknown destination. I spoke with AT&T yesterday who told me not to worry about the 14 day return window, since I can prove that I returned it in time and that all fees/taxes would be refunded to me when the phone was received. How long should I give Newgistics before I start to panic?