Even the best vaccine, Pfizer, does not guarantee 100% that you won't get corona.... I think it's over 90% after the second dose, but there is still a chance you could still catch and spread the rona despite getting the 2nd dose of the vaccine..... so yes, continuing to wear a mask would be the most responsible course of action.
Also, I'm not sure how long it takes for the vaccine to actually work so that might also be a factor.