'library' or 'require' call not declared from: 'rgl'

I'm checking a new release of vcdExtra via win builder with R-devel 
2014-10-29 r66897
and have run into a Warning I don't know how to fix.

I have one S3 generic, mosaic3d() that uses rgl and don't want to have 
rgl always loaded
via Depends:.  Instead, the mosaic3d.default() method includes

   if (!require(rgl)) stop("rgl is required")

This always worked in the past, but in this testing cycle, I got a slew 
of "no visible global function definition for ..."
all rgl functions.

I revised DESCRIPTION to include:

Imports:  rgl

and NAMESPACE:

import(rgl)

All the "no visible global function definition ..." went away, but I'm 
stuck with

* checking dependencies in R code ... WARNING
'library' or 'require' call not declared from: 'rgl'
See the information on DESCRIPTION files in the chapter 'Creating R
packages' of the 'Writing R Extensions' manual.

How can I solve this?

Michael Friendly     Email: friendly AT yorku DOT ca
Professor, Psychology Dept. & Chair, Quantitative Methods
York University      Voice: 416 736-2100 x66249 Fax: 416 736-5814
4700 Keele Street    Web:http://www.datavis.ca
Toronto, ONT  M3J 1P3 CANADA