RP Bug? [CLIENT / SHOP]

Okay, so. I had a little extra RP and Fizz is on sale so I decided to buy Fizz with RP (440), but I unexpectedly, I forked over more RP than intended unintentionally and without even knowing. I had 1320 RP, so I decided to purchase a 440 Fizz which leaves me with 880 RP left over. However, I now have 440 RP, half of what I was supposed to receive.

I opened the shop, and clicked on Fizz on the Champion Sale currently number 9 in the large central box. This led me to the usual Champion selection screen where you can purchase a new champion. I then clicked Fizz's portrait, not the UNLOCK button. I looked through his Abilities, Lore, and Tips respectfully and returned to the champion's skin selection and clicked UNLOCK CHAMPION, then I unlocked with RP. The screen showed 1320 - 440 = 880, perfect calculation. But when I exited the shop, I had 440 RP ... O___O;;