After Weirdmageadon,Stanford set out to "study" or give his opinion on the others in town and people he had never met. Example: Soos, Wendy, Linda Susan, Robbie etc.

After giving his opinion on others, he was only missing one person: you

Being lost for 30 years in different dimensions, he was obviously missing out on the new "trendy" things young people were into, like rap music, online games, etc. And you, being the same age as Mabel and Dipper, I didn't know you very well either. Stanford looked at you while you were in the booth and saw that you were using your cell phone

"What's that?"

He ask, half closing the journal where he wrote down his opinions of others. Obviously he didn't know what that was because he missed 30 years of Earth