Although it wasn't an issue of tartan, a friend went through something similar with his skodie (vest bikers wear, also called colors).

His father had served in a particular unit in Vietnam. Stenz found a patch from that unit, and wore it on his skodie to honor his father (sound familiar?). Another member of that unit saw it, and asked him about it: when it was explained, the guy bought Stenz a drink.

Now, the plural of "anecdote" isn't "data", but it seems to be an accepted practice here in the States to wear certain military symbols to honor family. To me, the tartan would be one of those "acceptable symbols"...