is it common? not always but sometimes....
does it means its time to replace it?

 

Is this a stock intake or after market? Many times the way the air is brought into an aftermarket intake on mostly b series, will cause a whistling sound at certain rpms. If the noise is new, not 100% sure but you could check to make sure everything is secure, clean your filter, or replace the filter. Good luck.

 

okok thanks! I will take it out and wash it with water