There is this yellow tag stuck out of the bottom of the gimbal, like peelable sticky label sort of thing.  But because it is at the bottomof the gimbal, I can see what it is other than the yellow bit like a paper tag that sticks out.
Is that part of the packaging or I should not touch it ?

Anyone knows.

Doesn't seem to affect anything though.

No one is really sure but it is attached to a piece of plastic covering the back of the gimbal and probably ensures the gimbal doesn't tap anything when the gimbal does its startup manoeuvres.
Just leave it there.

You can remove it if you want. It doesn't affect things either way.

http://forum.dji.com/thread-70471-1-1.html

Hy Fred,

It is really a matter of your choice: you can remove or let it there. It won't affect anything.
Cheers.

Just a scuff preventative film during shipping like on a thousand other electronic devices . I peel all the clear liners off of everything .

I left mine in place and, so far,  I have had no problems with crashes or app and f/w updates.  Just sayin'  :-)

Just got my Mavic last night and my  first thought that it was a a moisture detecting sticker

And here I went to all kinds of trouble to remove it.  It was quite difficult to remove.  Heck of an adhesive.  I figured it had something to do with the shipping protection, so I jumped through the hoops to get it off.

If it does not have a federal note on it you can do what ever pleases you.  I chose to leave mine in there.

Have you ever had an expensive couch and left the packaging on to protect it? Well its the same thing. I crashed my mavic and luckily i left it on. It stopped the top part of the gimbal from scratching the body of the mavic. The camera doesnt work though =)