Hummer H3 blowing white smoke on startup, head gasket fear setting in

Not a great way to start the week, walked out to my H3 this morning and when I fired it up there was a pretty noticeable cloud of white smoke from the exhaust that lingered for a good thirty seconds before clearing up. Drove to work and the temperature gauge stayed normal the whole way, no overheating or coolant loss that I can see in the reservoir, but I know white smoke usually means coolant getting into the combustion chamber somehow. I'm really hoping it's something less catastrophic like an intake manifold gasket rather than the head gasket, but I also don't want to ignore it and end up with a seized engine. Looking for an Al Quoz Hummer express repair shop that can diagnose this properly, maybe do a compression test or a chemical test on the coolant to check for exhaust gases before we start taking things apart. Dynostar seems to work on a lot of Hummers based on what I've seen in some owner groups, they apparently know the Atlas engines pretty well. Anyone with an H3 or similar GM truck platform dealt with white smoke on startup that wasn't a full head gasket failure, what else should I be checking before I panic and start out pricing engine rebuilds? Also wondering if the extreme summer heat here can cause gasket issues to show up that were borderline before, like maybe a small leak that only becomes noticeable when the engine heat cycles between our insane daytime temps and cooler nights.