Actually, it is hard to say if you over or under hydrated. Hydration rates are very individual and need to be determined for each person. The method is easy, weight pre-run before dressing and then post run after disrobing and drying off. If you gained weight, you over hydrated. If you lost more than 1-2% body weight, then you under hydrated. Water weighs about 8 pounds per gallon so if you came back a half pound light, then you would add 2 quarts to the run period.
As far as the soreness goes, look back to compare your 10 mile course and previous day's activity with the previous long run's. Did you run the day before the 14k? was the 10 mile course hillier or flatter than the 14k? Did you run faster? Look at the total week's distance compared with the previous weeks. Also, was it markedly hotter yesterday? Finally look at the other activities for the week. Did you do something extra that could have left you a little sore? Any of these items could create post run soreness - along with simply being sore from the run.
Make sure that you are stretching post run - while still warm. Many folks ice bath, but I think the current thought is a warm bath on the legs will make the muscle feel better post run. You may want to try that.
