I do believe there’s one in really small print, now that you mention it! But I think what’s meant is a larger, more visible one. You see it from a short distance but not carefully scrutinizing it and say, “yoyoexpert.com? I think I’ll check that out.”
IMO, the web address should be below or part of the logo for every contest banner, etc., too. Generally the address does appear in generic font for contests, which is totally adequate.