Front diff
 

i happend to be towing something and while exiting the neighborhood its a pretty steep incline so i turned the awd on. i immediatly forgot about it and left it on. driving down the highway roughly 20 minutes and the front diff blows a seal and i create a 5 lane wide smoke screen. i turn the awd off and limp home. I got under the car and can wiggle the front driveshaft a good inch or so. is this a common thing? did the towing do it? we don't generally leave the car in 4wd or awd just when we need it.