I'm not sure if it is either new or surprising.

I did an experiment some 3 years back from within a corporate network -- the difference being that it was done on a desktop, not mobile. The sequence of events was roughly:

- Spin off a new VM

- Create a brand new email address with fictitious identity

- Sign up to Facebook using the newly created fictitious identity

Result: The suggested "friends" were folks in that building (who were on the same network).

(The experiment was performed to demo how creepy such networks are.)