Wirelessly posted (BlackBerry: BlackBerry8530/5.0.0.1030 Profile/MIDP-2.1 Configuration/CLDC-1.1 VendorID/417)
"Why would AA even let me put it on hold in the first place if they're going to cancel it because of overlapping flights?"
Because it takes AA's computers some time to discover the overlapping reservation; that's why.