The false meme lives on:

No one thought to raise objections to Mormonism when Mo Udall ran for president, nor even when Mitt’s father, George, made a bid.

In fact, some raised objections in both cases, and opposition to a Mormon candidate was approximately as strong then as it is now.  If it was never as central to the campaign as it has been this year, it is partly because Romney’s father and Mo Udall did not run as a religious conservative and as the spokesmen for religious and social conservatives.  Romney is appealing to a constituency that was always going to be less receptive to him.  It is also the case that the media have pushed this angle since before Romney announced his candidacy.