Your Mops was away on a business trip when you were born. This is the first time that you met him.
By the way, in case you are wondering why you call him Mops instead of Grandpa . . . can be blamed on your eldest brother. He never was able to say Grandpa and my dad really never wanted to be called Grandpa. So, when your eldest brother called “grandpa” something, it came out as Mops and has stuck ever since.