MMA fighter Luis Peña -- aka "Violent Bob Ross" -- tells TMZ Sports the time has come to renegotiate his contract with the UFC ... and he's confident he's gonna get it.
We spotted the 26-year-old after he landed at LAX on Sunday following a controversial split decision loss to Matt Frevola at "UFC Fight Night" on Saturday ... and it's clear Pena thinks he got robbed.
Pena points out that Frevola trains in Tampa -- where the fight went down -- and he suggests there may have been some "small town bias" affecting the judges' cards.