This is not new.
As Ron says, this is an additional 'earnings credit' up to 1200 per year. So if you served on active duty (using different formulas for 1940-1956/1957-1977/1978-2001) you get a max additional earnings credit of 1200 per year.
Asking about military service is a standard question when applying for social security retirement (not disability, a different matter altogether) so although this is not an urban legend, misleading statements like, ‘you have to ask for it’ make good information seem questionable.
Check the SSA website, you can apply on-line now and even there it asks if you have military time, so it's not something they're trying to hide.
And something a coworker found out researching this a little deeper, social security retirement benefit is essentially based on your 'high 35' of earnings.
Generally, for 'most' people who apply for retirement at 62 or older this means that effectively even with the additional credit, military service may not account for any of the high 35, and the social security folks can figure this out in short order, so if they don't ask to see a 214, it's because it wouldn't have made any difference.
But if you're retired from active duty (as some of us are), and essentially not work much longer thereafter (some of us are trying not to

), this may have an impact.
And by the way, the coworker who called SSA to ask about this was told they’ve been fielding a lot of calls about this ‘hidden’ benefit lately and didn’t know why, but because they don't ask for a 214 if you don't need it, they don't automatically explain why you don't need to present the 214, which may lend some air of 'hiding' something. She said she will make it known in the organization to explain they already have the numbers figured in.