There is a new NOTE. This line with \& used to be acceptable.
I am not seeing what the suggested replacement is.
* checking Rd files ... [4s] NOTE
checkRd: (-1) bivariateNormal.Rd:42: Escaped LaTeX specials: \&
The full example is
\note{
Based on the \code{galaxy} example on pages 204--205 in
\emph{S \& S-PLUS Trellis Graphics User's Manual},
Richard A. Becker and William S. Cleveland (1996),
\url{https://www.stat.auckland.ac.nz/~ihaka/courses/120/trellis.user.pdf} %% works 19Aug2019
}
Rich