Text on home screen

Hello, today while I was about to check some emails on my iphone I saw a text message on my home screen (not a pop or alert message, not a message from notification center) that I have never seen before. I actually didn't know that it could be a text on that area of the iphone. Very strange. I spend a few hours trying to see where that text came from, but nothing. Neiter my calendar, address book, notes or any other app with reminders had that specific text.

Anybody can help me, just trying to know how that text got there. Hoping not a hack, text from the carrier or something of the sort.

Thanks!

PS. I'm attaching a screen capture of that weird text (by the way, I'm in Mexico so yes the sentence is in spanish)