Where's Adah?

So, I was sitting in my recliner this morning doing my own thing and I looked over to see that Adah was going after a ball.  I thought, 'ok, that's great, she's going to play with that ball.'  Next thing I know I go into the kitchen to do something and think again, 'I wonder where Adah is and what she is up to now.'  I came into the living room where she was last seen going after the ball and she isn't there anymore.  I noticed the stairway gate was open and started heading up the stairs.  I didn't see her on the first flight so I continued up the second flight.  Low and behold, there's Adah three steps from the top...with the ball in hand!  I sometimes let her climb up in front of me on the way to nap or something but she hasn't ever tried to get on the stairs on her own.  It's just never been a problem.  Plus, the gate is almost always closed.  I guess we are going to have to be extra careful to make sure it gets closed for sure!  She seems pretty steady on them by herself, but when I watched her get to the top she was ready for a rest and almost fell backwards off the top step.  She was way too close to the edge!  It was pretty funny though to see her going up all by herself.  When I found her I said to her, 'what are you doing, miss?' (in a playful kind of way) and she just got really excited and giggled and tried to go even faster.  So sweet!