Could be... have you been doing some circle work??!! lol,
Can you feel the 'shudder', or mainly hear it?
Is it sort of like a howling noise?
Has it been abused lately? tight cornering, spinning? anything out of the norm?? haha...
Could just be coated, give it a service see how it goes, otherwise could just need an acid bath.
"Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind."
- Theodor Seuss Geisel