Does anyone else have the problem that they're not upgraded even though their status meets the criteria for being upgraded?

IE I'm a gold elite, and have had multiple times where i've been within less than 3 days of my flight time and when I called in to check my seat, I haven't been upgraded. Shouldn't NWA and CO automatically upgrade me if there are seats available? Why do I have to call in and have them do it?

Thanks..

Tim