When searching for a telephone number on my smartphone, I head straight to Google and enter the name of the establishment.

I then clicked on the Call button and was presented with an interesting new dialog box (which I saw once the call was completed and I was returned back to Safari Mobile).

Google was asking me to validate the number it had provided. 

I tried to reproduce this dialog box by clicking the call button (for the same establishment and some others in the area) but it never reappeared. 

Maybe the number was flagged as wrong by someone? Maybe Google periodically checks the validity of all numbers? Have you ever seen this before?