whistle at idle, increasing in volume through RPM range?

[06TurboScoob]

Have 2006 Baja Turbo. 76k.
Dealership installed new short block, 600+ miles on it.

Last couple days I've noticed a 'whistle' that starts at about a grand, and gets louder (not REAL loud) as the engine builds in revs.
Turbo kicks in at about 3k? Whistle starts up before and continues through the effective turbo spool.

Boost leak? turbo shaft? anyone got any more comforting ideas? lol