iPhones are really amazing. They do some almost space age things but I never knew it was doing this. I just shut mine off and you may want to as well... 

I just saw this anchor on youtube describing how her husband got mad because he knew she had been to the mall and what time she was there. She describes it and how to shut off this feature in your location settings. I had no idea about it. It's supposed to be there to help you so when you go somewhere, your phone can recommend places in your area, it may however get you in some trouble.