heatmap

Dear R-users,

I am using R-1.7.1. on windows 2000. When I use the heatmap() function, I
found lines on the dendorgam are not well connected. For example, the two
dendrograms produced by the following have this problem.

set.seed(1234)
heatmap(x<-matrix(rnorm(100*30),100,30))

Is there a bug in plot(dendrogram object) which heatmap used?

Thanks,
Ming-Chung Li