Although I've searched, I can't find any mention of what seems to be an odd bug.

I just received one of the letters from "a friend" that you get after using a shout. This one, though, had "[...]" (without the quotes) instead of the usual word wall location.

Has this happened to anyone else? Is there any way of dealing with it other than just shrugging and ignoring it?

I still have quite a few shouts that I haven't learned/completed, so it's not as if there aren't any left to find.

I know it's not that big of a deal; I could find the locations on UESP for example, but I hope that this isn't a sign that I'll be getting incomplete/useless letters from now on.
Does anyone have thoughts/suggestions?

Maybe the shouts you have missing are in dungeons you aren't supposed to go to except for certain quest lines, hence blank radiant quest?

That's possible, and I hadn't considered it. Thanks for the suggestion!
If the game (maybe a recent patch?) is going to those lengths to help me avoid breaking quests, I'm very impressed and appreciative.

It even had the brackets?

I've never seen this - maybe it's a location you've already cleared? An odd bug in any event.

I've had something that could be considered similar: one of my reward weapons at some point (maybe after 1.4) had it's name changed to something like Axe of [alias=hold_name].

Yes, it even had the brackets.
Since this is the first time it's happened over almost 400 hours of play with several characters, and in light of your weapon name experience, I'm inclined to think it's a bug introduced by the most recent patch.
I'd certainly like to hear from anyone else who has experienced this minor but somewhat vexing issue.

It's like that one letter from the DB saying I know what you did but you don't know it's from the DB.

Yep, same here. I've had this letter more than several times whilst playing as my first character. I just wrote it off as a bug. Maybe my character still has them so I'll try finding them later.

ride-the-spiral, thanks for the information.
Have you ever received proper/normal letters with actual locations, after having gotten the ones with the blanks?
BTW, I'm in the Tokyo area, too, more or less.

nvm