Reviewed play in Greenbay game today

[DrMooreReferee]

It was a punt. The Oakland player fielded it, made a couple moves, and was hit and the ball pops out. The ball ends up in Oakland's endzone where GB falls on it.

The call on the field was that the player was down before the ball came out. It was reviewed.

Now, on the replay you can clearly see the ball come out before he was down. You can also see the covering official coming up and really selling his call. He was pointing to the ground and getting his spot. Now, you cannot hear a whistle. Which leads to my question......

After review, it was ruled a fumble and a recovery by GB for the TD. I really could care less, but I can't help but wonder if the covering official was blowing his whistle. And if he was, why wouldn't this play then be called an inadvertant whistle?

I'm not well versed in the NFL rules and mechanics. So, maybe there's something here I'm unaware of. Maybe the guy wasn't blowing his whistle. But being a high school official, I know if I was the guy making the call I would also be blowing my whistle.

Any thoughts?