Upshift delay applies to all shifts when the system is activated, not just 1-2 or 2-3, all shifts are delayed due to the upshift delay solenoid. It in effect makes the throttle valve "shorter" which makes the trans "think" you are accelerating harder than you really are, which causes the transmission to delay the upshift, which would be normal for hard acceleration. It helps warm up the catalytic converter and O2 sensors. If it is delaying upshift for the first 5 minutes or so, then the system is working as it should and i wouldn't worry about it. maybe I'd worry why it didn't do this before, but not about what it is doing now.