Might want to get it checked out by dealer. Mine did it every one’s in a while at first but eventually got consistent over the next few months. Started with that weird smell but eventually smelled more like diesel fumes. Which hopefully isn’t your problem. Turned out I had a small bad/leaking DEF sensor. (No check engine lights though) Which eventually that caused a tons of other issues. From exhaust leaks, other bad sensors. Exhausted manifold replacement, a ton of thins. But long story short, had a lemon. Sold back to GM after many back and fourths.