As long as it’s within reason. Getting paid As little as 7 cents a minute while stationary is hardly getting paid
Next time have them add a stop on their route. If they take more than 3 mins at their stop, their fare will be readjusted to fairly compensate you.
I always do it because they usually offer to buy me something or give me cash for stopping
Granted, I am unusually luck that most of the people who ask me to do this are that nice, so take that with a grain of salt
As long as you don’t end the trip, Uber has record of the time and mileage for your trip from point A to B. You are serving the customer and being compensated for the service as until you end the trip!
As long as you keep your app running & don’t complete the trip it calculates ANY & ALL.
Just “gently”(lol) remind to make these types of changes in their app
UBER allows up to 3 stops & they allow UPTO 3 minutes at each stop otherwise they will be charged extra (per UBER support & a customer rider of mine who does this often on her way to work, she said it DOES tell them this info ONLY if they’re paying close attn 
)
I’m buying the 5 star rating signs to display and encourage rating me and tipping me.