IP after a game shows more IP than you have, and upon closing and re-opening client, the IP adjusts

Trying to get enough IP for a 4800 champ, I go to work on playing games. I started around 4600-ish. After playing 2 ranked, my IP showed as 4860. I went to purchase champ and the IP slot was greyed out as if I didnt have enough. So I restarted my client and when I logged back in, my IP was significantly lower than the 4860.

So I thought maybe my brain was just being stupid after work and I saw the wrong number. Fast forward a couple more games, IP shows as 4960-something. I go this time to purchase champ. Same issue. Restart client again, my IP reloads as lower than before. I got screen shots this time, though.

Is this a thing? Or does Rito just hate me and enjoy crushing my hopes and dreams?[slayer-jinx-unamused]