Yes. That's what happens when things get old and dirty.
I have a measles ball on my desk, that I broke a chunk out of, and it is almost cream colored. It's loaded with stained half moons from jumping and breaking.
I clean my measles balls with Comet Cleaner, then Aramith Polish and lastly with a Diamond Blue Mist Polishing Spray.
I have three measles balls....2 used and 1 new....they all still look alike and are white.....how you treat your equipment
determines how it holds up.....same applies to pool cues. Pool balls will discolor when not properly maintained or stored.