It doesn't make much sense, but it's pretty typical on FedEx's part. Not that I have anything against them - they're quite fast and extremely reliable in all of my experience, but what they do on the back end always seemed strange to me.
As I said in the other thread, I've worked for a company that ships via FedEx for a long time. I've noticed that pretty much any package that leaves the state of origin goes through Memphis, even if it's being delivered to the neighboring state. Stuff that stays in-state usually passes through the state's largest FedEx processing facility and then moves on to its destination. That's usually the case, but in no way is it a foregone conclusion. So, in essence, I'm not surprised yours traveled to Memphis, despite being in-state.
I was getting a little worried my delivery would be delayed, as it hadn't even left Memphis when I went to bed last night (it had been there since 4:09am Monday morning), but it's on the truck for delivery now!