I'm having bottle issues

So one of the new ways I want Daniel to start being independent is by holding his own bottle during a feeding.  This morning I figured was a perfect time to start...I mean he's held his bottle alone on and off so I know he knows how. Well whatdayaknow...he held it alright...for a few secs then he starts a game of in and out.  He puts the bottle in his mouth and then takes it out to look at it...then in again...then out again to look at it...then in again...*sigh*

Now if this is the way he wants to eat...whatever...except that every now and then he loses hold of the bottle and then starts fretting...you know that not really crying type of cry.  After a few round of this I start to get frustrated because this is taking more time then if I would just feed him myself.  I take a deep breathe and hand him the bottle for the umpteen time so he can start the in and out game yet again. I try to remember this is all part of building his independence...and besides that bottle will only last so long during each feeding.