You did the right thing. Spiders can nest in the burner tubes of your BBQ and cause a propane buildup, resulting in a fire or even an explosion. Of course, a spider that big wouldn't be able to get into those tubes... so, make sure you have a full mug of beer with you when you open your BBQ. Then, if necessary, you can douse the bastard with beer and momentarily immobilize it while your fire up the Barby and roast it's hairy little ass.