I'd definitely crack the bleeder screw and make sure no air is in the system, air in the system allows the Dex Cool to become more acidic, which is bad for seals, coolant elbows, old nylon 6,6, LIM Gaskets, etc
At least that is what I have read.
I drilled a little 5/32" hole in my thermostat, right behind the gasket area, so when I filled my radiator I could squeeze the hose to "burp" it a bit, the hole lets the air trough, without you having to get it up to temp and bleed it, but I still bled mine afterwards just in case.
2006 Pontiac Grand Prix GT with SC
1996 Buick Park Ave NA