Intriguing? It's bloody annoying! Will never do it when you want to show someone!
I am still, occasionally, cracking the middle G on my tenor....have to get the embouchure just right (Nothing wrong with the sax)
Oh, and BTW, ilovebech, you have an intermittEnt fault in your spell-checker
Check the spring on the normally closed f# aux key, it's easy to unhook as you're cleaning, and can give this sort of intermittent problem. If it's not that check the other keys that are held closed by springs - and also check they open when they should, not sticking closed.