When I did my timing belt change, per Bart's instructions, I seem to remember one of my cams sprang to the 12 o'clock position, but the other jumped to the 3 o'clock position. I think it all depends on how the valves are pushing on the cam at the time you release the tensioner.
Like SlowPro said, as long as everything was lined up when you took the tensioner off, and you haven't rotated anything, then when you line everything back up it should all work out just fine. DO rotate the motor by hand a few times to make sure that everything is happy before you turn the key.
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong, it usually turns out to be impossible to get at or repair."
-Douglas Adams, Mostly Harmless