$\ce{CO2}$ reacts with water which is why it enters and exits solution slower than other gasses (if I understand correctly this is why carbonated drinks bubble gradually instead of all at once).
Henry's law is an approximation that assumes the gas solute does not react chemically with the solvent.
Is the Carbonic acid reaction significant enough that Henry's Law does not work for $\ce{CO2}$?
What about in the case of blood, where the reaction is catalyzed by the enzyme Carbonic Anhydrase?