OCD truly can kill a pipe experience...good thought, Mon.
Whistling is disrupted air flow. This may or may not mean off-centered drilling, stepped-drilling (different size holes connecting somehow), or even the shape/smoothness of the draft hole.
I chamfer my tenons in a unique way...rather than a 45° angle drilled with a particular bit, I carve them with a particular knife. The result is what I call a "trumpeted" chamfer, and it looks like the bell of a brass instrument. Pipe stems that hadn't whistled before will do so now, because of the difference between the opening at the mortise end in the shank and the tenon end on the stem. Sometimes the stem not even attached to the pipe will whistle when a test draw is taken. The whole point of the chamfering is to reduce the sharp, angled or rough surfaces the pipe may have from bowl to button, which will disturb smoke-flow, where usually moisture will develop as the pipe is smoked. I developed this because I do smoke cheaper pipes, and the stem tenon didn't always line up with the draft hole in the shank (at the mortise).
The subsequent, slight whistling actually became an indicator I was puffing a bit too hard on the pipe after I had added said chamfering...if I concentrated on not making it whistle, suddenly the smoke was cool again. This helped me as a beginner and gives me a reminder if I'm smoking too anxiously and will save my tongue even in my current "intermediate" stage. I have almost zero moisture issues these days.
So no, whistling is not a direct indicator of bad "flow dynamics," but it sometimes is. If the pipe smokes well, then it's merely an irritation. Not to mention, don't blow into the pipe to make the noise if you don't like it...concentrate on drawing instead. :lol: