confusing "Warning: Imported from"

line 12 and 13 of my source ATC2.hs
(http://hackage.haskell.org/trac/ghc/ticket/955)
are:

> import HsName (HsName(UnQual))
> import PropPosSyntax

UnQual comes in via PropPosSyntax and HsName but is not used.

However, I would expect a warning for my explicit import of UnQual from
HsName. Instead I get:

ATC2.hs:13:0:
    Warning: Imported from `PropPosSyntax' but not used:
               data constructor `UnQual'

Is this a known (or easy to resolve) issue?

Christian