@Linkat,
Surveys and studies about social interactions or situations make for interesting collections of data, but they rarely (if ever) provide a good foundation to base fundamental life decisions upon. Either they scare the bejeesus out of a person with nightmarish 'truths', of they can provide a false sense of security because odds seem so 'low' anything bad could happen.
The children of today live in a world that is nigh impossible to compare with the world we grew up in (I'm talking about 25 to 50 years ago). The internet makes for a fabulous, if at times very, very frightening, means of communicating with each other. People from all over the world can find each other with a few clicks and swipes, and that also holds true for that boy living close to an hour away.
Truth be told, he sounds rather harmless. Life of the bullied is a lonely place I once resided in as well. Children who show kindness and understanding are a godsend at times, and the desire of a bully victim to latch onto them , in part for protection, in part out of loneliness, is big. It was for me.
Your daughter won't be protection, due to physical distance, but she can obviously be a friend. If you truly want to find out if this boy is obsessive about your daughter is to get in touch with his folks, and see if they have a global indication of how many people he texts each day. If he stays in touch with four or more children as well, I reckon it's nothing to worry about in the first place. If it's just your daughter, than it might be prudent to remain observant...
But, following in everyone's footsteps here, let your daughter handle it. Being socially adept at handling boys is going to be very useful down the road of your daughters life. So every lesson she gets in it is going to pay of its dividends later.