I believe the answer to your question lies in the question itself: "if you actually smoked it that long without checking the temp".
You cannot cook by time and temperature, you always need to cook to a final internal temperature. If you check the temperature periodically and remove the salmon when it reaches 145F, you should be fine.
I often cook my salmon on a cedar plank that has been soaked in water before use. Although many recipes call for cooking without flipping the fish, I normally flip it half way through so both sides of the filet get similar exposure to smoke and to the cedar oils. Be sure you use cedar that is certified for culinary use. Some types of cedar are toxic.