Question about a post

Brian Carnell questioned a statement I made in my post Beware the Internet. He writes:

Okay, if you're going to call your blog Anti-Media and have your tagline as, "Dedicated to exposing what the media lies about, what they won't tell you and what they don't want you to hear," it doesn't help to make stupid mistakes like this,

According to Tom Maguire, an internet researcher has uncovered an AP article from 1992 in which Kerry claims to have served six months in Vietnam instead of four. . .

But for Kerry, who spent six violent months commanding a patrol boat on the Mekong River, there's always been a ring of truth to allegations of abandoned Americans. By Christmas 1968, part of Kerry's patrol extended across the border of South Vietnam into Cambodia . . . .

Kerry, of course, never says that he spent six months in Vietnam -- that statement is made by the Associated Press reporter without any sort of attribution by Kerry or anyone else.

Brian, where do you suppose the writer got the idea that Kerry served in Vietnam for six months? Pulled it out of the air? Made it up?

Or perhaps he got it from Kerry's interviews with the Boston Globe where the writer interviewing Kerry wrote:

The mounting losses made no sense to Kerry. The boats went up a river, showed the US flag, perhaps killed some enemy, and returned to base without taking any territory. Six months earlier, Kerry had been a gung-ho skipper eager to lead his men and be a hero. Now he felt the mission had changed. He replaced his dream of a life in politics with a path of protest.

Well, no, that couldn't be, because the AP writer wrote his article in 1992, and the Globe article appeared in 2003, when Kerry agreed to a series of interview to highlight his war record.

Maybe both writers made it up? Or perhaps, just perhaps, Kerry gave them that impression and then chose not to correct it when they wrote it down?

Try to imagine doing an interview with someone about their Vietnam service. At some point you decide to close the article with a comment about the time he spent in country. Do you ask the interviewee how long he was there? Or do you try to figure it out for yourself? If the writer counted the months that he served on patrol boats (clearly stated in the article), the most he would come up with would be four months (December thru March). It seems unlikely a writer would conflate that to six months at the end of the article.

On the other hand, if the writer asked Kerry, "So how long were you on the patrol boats?" and Kerry responded, "About six months", why would the writer question him? In the end Brian is correct. We do not have a direct quote from Kerry stating that he spent six months on patrol boats, but what we do have is two different reporters making the same "mistake" 11 years apart.

What seems the most likely cause of this error?