Why did Frodo Volunteer to take the Ring?

OK. It's been a while since I read Fellowship, so my answer is based on the movie. I know, I'll read the books again real soon. My theory: Frodo volunteered to take the ring because it was already starting to work its magic on him. When Elrond asked Frodo to put the ring on the table in the middle of the circle, I thought Frodo showed a tad of reluctance to let it go. When everyone else was fighting over what to do with the ring, who should bear it and all that fun stuff, Frodo was rubbing his forhead like he had a migraine coming on, and that wasn't an ordinary gosh-that-nasty-dwarf-axe-made-a-big-bang-when-it-shattered flinch. Frodo was acting like a junkie going through the first stages of withdrawal. Yes, Frodo was on his way to becoming a ring-of-power junkie.