It could be for a lot of reasons. Possibly that with the extra calories burned with longer sessions of running, your body just needs more input. If you are really hungry, eat a little something, but without knowing your current diet, your stats or ultimately your goals, it's impossible to say "how much." But one way to prevent hunger pangs and especially binge eating as a result of hunger, setting up your diet so that you are eating your daily caloric needs in 5 or 6 smaller meals throughout the day (eating every 2 or 3 hours) will help tremendously.