I like Selena but while reading this story I also thought it sounded a little bit fake; him not taking a picture with her, even though it makes sense since he says he didn't recognize her, is very convenient and also the whole thing of him talking with her and then a few days letter reading an article about Selena and realizing that she is the girl he talked to is what sounds the most fishy to me.
Anyway, I just checked the post and his facebook profile aswell as his mother's (
at me stalking them to get more information) and their profiles seem pretty legit, they have pictures of themselves from ages ago with a nice amount of likes and comments and is obvious that he is very into music and just like Revival said, it would be very weird to buy that set and then say he got it from Selena, based on his likes he doesn't even likes Selena's music so it would just be weird to say that she did such a nice thing if not true and get his mother involved in this.
So if indeed Selena did this then she is amazing for this