As an M.D., I agree 100%. On top of which, I'd expect vaping to do the actual opposite of adding excess water into the respiratory tract (lungs). With the heat produced from the atomizer/cartomizer, I would expect the respiratory tract to become dehydrated rather than become excessively hydrated, which is why replenishing with water is important for hardcore, all-day vapors.
Otherwise, like Vap3rV3nom stated, any excess fluid/liquid/etc. in your lungs will be reabsorbed into your body's circulation via pulmonary capillaries. Result? Might pee more often than usual.
Think of it this way - more water and tiny food particles get lodged in your lungs more often than you think. When this happens, very small parts of your lungs collapse to consolidate the water/food particles that are lodged in the small passageways. Medical term is "atelctasis." Tiny atelctases occur often, even on a daily basis, with everyone - how come we don't really notice it? They are so minuscule that our body amazingly compensates and rids of the tiny particles by dissolving and eventually absorbing them into our blood circulation via pulmonary capillaries (vessels in the lungs). When that's all done, the collapsed tiny part(s) of the lungs reopens and everything goes back to normal. Once it is absorbed into the blood circulation, it filters at our kidneys and we simply pee it out. Amazing, in my opinion.
Long story short - don't worry about it. Happy vaping!