Hello....Mami, why are you so long?

I had recently learnt how to call Mami on her handphone. I did not memorize her handphone number but used the phonebook feature on the house phone. Since then, I would always call Mami on her handphone everytime she goes out. Mami is a little irritated because I call her 15 minutes after she leaves the house. I would complain and say "Mami, why are you so long"? I am extremely clingly to Mami recently. Mami could not understand why.