Not that big of an issue atall..

The flame if it does get in the bowl and travel 2 -3 inches inside, which it normally wont unless your dry hitting it.. and ignite the glue is hard to think of, especially with weed stopping the flame.

I used some silicone and super glue to fix my 2 foot waterbong, it worked swell untill i dropped it on someones lawn inside a bathroom towell. i was on m way to sell a fixed bong :-p