Summoner Name change for free

I was curious to see if the name I wanted to change to was available, it was, and I clicked "Purchase with RP" and I didn't have nowhere near enough for it. It prompted me to sign out, name was changed, and even in purchase history it shows it was made with RP despite not having the rp. Curious if this could be like a free name change, one time, for a newer account? Is it going to be charged, the RP needed, to my paypal that's linked to my account, or is this just a bug? If anyone knows anything let me know please.