There is some, but negligible risk, of air borne contamination if there is significant air movement but is has to be done to take SG samples. Most of the risk is from not sanitizing around the lid of the fermentor before it is opened.
You have really shown a great amount of patience and restraint not having looked at the fermenting beer multiple times just to see what is going on. Pitching the right amount of yeast and having the fermenting beer at the right temperature doesn't require keeping constant visual tabs on it..
I ferment in glass carboys so I can do a visual check without opening the fermentor. Doesn't require any amount of patience.