warning: implicit conversion from matrix to string

[Vic Norton]

How do I get rid of implicit conversion warnings when printing an  
array of strings of the same length? For example the script

        % test2.m

        global SEC_PER_HOUR = 3600;
        SEC_PER_DAY = 24 * SEC_PER_HOUR;
        SEC_PER_WEEK = 7 * SEC_PER_DAY;
        
        function  date = time2dateEST( time )
        ## The date returned is the "%Y-%m-%d"-formatted EST date
        ## corresponding to time.
                global SEC_PER_HOUR;
                time -= 5 * SEC_PER_HOUR;
                date = strftime("%Y-%m-%d", gmtime( time ) );
        endfunction
        
        dates = zeros(5, 10);
        time = 1082667600;
        for i = 1 : 5
           dates(i, :) = time2dateEST(time);
           time += SEC_PER_WEEK;
        endfor
        
        for i = 1 : 5
           printf("%s\n", dates(i, :));
        endfor

produces

        octave-3.0.2> test2
        warning: implicit conversion from matrix to string
        2004-04-22
        warning: implicit conversion from matrix to string
        2004-04-29
        warning: implicit conversion from matrix to string
        2004-05-06
        warning: implicit conversion from matrix to string
        2004-05-13
        warning: implicit conversion from matrix to string
        2004-05-20

on my system.

Obviously the dates have been "converted" correctly. What is the  
problem here?

Regards,

Vic