is my airlock going to blow off?

[Brewby, my beer]

I'm using a glass carboy for the first time as my primary. I have the white rubber stoper and the 'S' shaped air lock.

My question is, after I put the stopper in with the air lock, the stopper rises up about 3/8 of an inch. Is this normal? is the stopper going to pop off the carboy?

Thanks.

 

[El Pistolero]

If the stopper and the mouth of the carboy are dry, that won't happen.