problems with max.col()

Hello, I think the following qualify as a bug
given:
x<-c(1,2,3,4,2,4,2,2,4,2,2,2,4,3,2,1)
z<-embed(x,4)
z
      [,1] [,2] [,3] [,4]
 [1,]    4    3    2    1
 [2,]    2    4    3    2
 [3,]    4    2    4    3
 [4,]    2    4    2    4
 [5,]    2    2    4    2
 [6,]    4    2    2    4
 [7,]    2    4    2    2
 [8,]    2    2    4    2
 [9,]    2    2    2    4
[10,]    4    2    2    2
[11,]    3    4    2    2
[12,]    2    3    4    2
[13,]    1    2    3    4

max.col(z)
 [1] 1 2 3 4 3 1 2 3 4 1 2 3 4
Why?     ^ ^

       1 2

or should be
 [1] 1 2 3 4 3 4 2 3 4 1 2 3 4
i.e. the first column with the max, or the last column
same if
z <- embed(x,5)
 max.col(z)
 [1] 2 1 2 5 1 5 3 4 1 2 3 4
where it should be either of:
 2 1 2 3 1 2 3 4 1 2 3 4
 2 3 4 5 4 5 3 4 5 2 3 4
or I am missing something?
?max.col does not return anything
R 1.7.0 on Win98
.
Heberto.Ghezzo at McGill.ca