Nope, Modern batteries contain calcium metal in the lead parts to decrease the tendency to produce hydrogen gas during charging by electrolysis of the water in the electrolyte solution. If enough calcium metal is present, the battery gassing is so well controlled that the cells can be "sealed" and their demand for replacement water greatly decreased.
Or.. in laymans terms it does bubble during charging but newer batterys of today require less maintanence.

lol
have a look
here for a most FAQ's of car batterys.
Out of curiosity, is it still charging ok?