Is "catch up with" not to get behind or lag in conversation due to the interruption of picking up my dry cleaning or "try to find out how grandma is doing lately"?
ex) People today are great at multitasking. I catch up with my grandmother on my cell phone while picking up my dry cleaning, or send a text message to my client while standing in line at the grocery store....
It means find out how grandma is doing and what he has been up to.