As someone who typically GMs, I'm accustomed to seeing resistances specified in monster stat blocks as "resistant to bludgeoning, piercing and slashing damage from non-magical weapons".
However the barbarian class feature Rage states that a benefit of raging is "You have resistance to bludgeoning, piercing, and slashing damage," neglecting any mention of magical weapons.
Though PCs encountering magical weapons may be rare, are there any other rules which stipulate that the basic rage resistances don't apply towards magical weapons?