Not a stupid question at all, Danette! And I'm [word censored] if I can answer it authoritatively, but I suspect that it's one of those 'you can do this, but we hardly ever do' things in English. Whenever there is an adjectival complement that follows 'be', we tend not to contract it when the subject is followed by a modifying expression like 'I got'. So you can say "This newspaper's torn' and that is no problem, but as soon as you add that modifying 'I got', the resulting contraction sounds odd -- and clunky.
If I had my Quirk & Greenbaum Comprehensive Grammar of English bible with me, I could give you a definitive answer, but maybe someone with more smarts -- or a Q & G copy -- will come along!