[mgcv][gam] Problem defining axis labels for non-smooth terms (via termplot)

Dear List,

plot.gam appears to be having trouble communicating its xlab and ylab
information to termplot.  A simple example:

library(mgcv)
x = 1:1000
y = runif(1000)*x^.5
z = rnorm(1000)*y
other = sin(z)
fit = gam(y~s(x)+s(z)+other)
plot(fit,all.terms=TRUE)
plot(fit,select=3,xlab="???")
     dev.copy2pdf(file = "This.pdf.needs.proper.labels.pdf", height = 8,
width = 8)

Any ideas for workarounds?

Many thanks as always,
Andrew