A thread stopper is an excellent idea! Some threads do seem to leak a bit. In fact, some leak a lot. I remember when the "How Many Spatulas Do You Own?" thread started leaking and before anyone could say "slotted pancake-turner" there were a dozen other spatula-related threads.

Come to think of it, much of the thread leakage around here could be avoided if someone would put a stopper in Skipy's beer bottle. (Insert smiley face HERE.)