When you say it kept signing you in and out of them, was it just the notification saying started / ended visit? Or was there an application that ran?
When the notification came up, can you press and hold it, to see the app details? Like how you would on the notification bar?
But, almost looks like an AirPush ad.
Look in your phone settings and Location. Check the applications list and see if there anything listed there that you don't know. But, that list only shows recent requests, and I don't know just how far back that list goes.
Or else run some type of adware scanner.
I personally use All In One Toolbox, but have run Avast, AirPush Detector with good success. Most scanners should be free to scan.
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