paste / system mystery

Dear R wizards:

under R-2.1.0:

eargs <- 3:5;
line <- paste(c("echo A B", eargs));
cat("executing from R: '", line, "'\n");
system(line);

Oddly, only "A" and "B" are echoed, not the eargs.  I had hoped that
line would be one string at this point, and for printing this seems to
be true.  However, unlist(line) still gives me the 4 components.  It
almost seems like the objects were not really pasted, but kept separate
[perhaps to conserve memory]---which works internally, but not
externally.

Is this my poor understanding of R, an R "feature," or an R bug?