Vivamus,
Just enjoy it and don't worry about it. I lost my Dad 3 years ago after he had heart surgery, and there is so much I wish I would have said to him. I wish I would have spent more time with him.
Imagine never having had the opportunity you are having now. Imagine what it would have been like if you never connected with your Dad. Imagine if you never got to laugh with him and talk with him like you are now.....not to share a smile with him. Isn't that what you were afraid was going to happen? But, now you are in the present...you are experiencing what you were afraid would never happen!
Enjoy the present, and not if it's going to last. You are building memories that you and your father will treasure for years to come. Do all you want to do together now. You lost him, but you got him back! I will never have my own Dad back......