I agree with your thoughts on the matter. Make sure you are hydraiting well and urinating sufficiently too. Many walkers and runners face this same situation. It really is not a problem as long as the swelling subsides within a few hours afterwards. If not, then you shoud discuss with the doctor. Please look at the website below for good info for you about your problem and guidelines for drinking to help alleviate it.
Please let me know if you need further clarification or want to talk more!