If you are using the vial rather than the pens you have nothing to worry about, the vials will get air in them as yuo draw out the insulin its the way they are designed, if they didn't get air in vacuum pressure wouldn't allow you to get a good insulin draw. Now the pens are different as they have a stopper that slides down as the insulin is withdrawn to keep the pressure equalized, the vials need to have air to do the same thing.
Mel, Maxwell, Autumn & The Fur Gang