Don't sweat it, there are far worse things people have done and it still turns out great. (Have a gander at Reevy's sticky post to live his adventures). 3 days is not long, and the yeasties will still be busy doing their thing, crapping out alcohol and cleaning up the wort. A bit of oxygen to keep them on their merry way won't hurt it at all. Good to see you are so keen on this whole exercise you have been watching the fermenter like a hawk. Take it from all the folks on here, relax, leave the yeast do it's thing and plan your next beer. Having a pipeline of brews will ensure you enjoy your last batch instead of needlessly worrying about your current brew.