Camping in a back yard with a friend, a creature looked into the tent at us, at which point hours were lost.

I was approximately 11 years old, staying overnight at a friend's house, "camping out" in his back yard.  My friend had fallen asleep quite suddenly, and I heard what sounded like an animal shuffling around in the grass outside of the tent.  Normally this would not have scared me, but for whatever reason, it did, just then. 
I turned and looked at the screen in the tent flap and saw a head, shaped roughly like a football on its side, looking in at us in the darkness.  It realized I was looking and quickly dropped out of sight.  
At this point I did what any normal person would do - I covered my head.  I looked out a couple of minutes later (so I thought) to find it was mid-morning.  My friend was still asleep, and I was thoroughly confused.  
I have no idea what I saw that night, and no idea what happened in the time from covering my head to the next morning.  Again, it seemed like a couple of minutes, but was actually hours.
Source of report indicates that the date of the incident is approximate.  PD