Origin of the "Pink Slip"

[Kim & Rima McKinzey]

>In a message dated 03/26/2001 8:31:42 AM Eastern Standard Time,
>Amcolph at AOL.COM (Ray Ott) writes:
>
>>  Probably not labor scholars.  For the blue collar worker up until quite
>>   recently, discharge or layoff would have been dealt with on a face-to-face
>>   basis.  Using a pink piece of paper smacks of bureaucracy and
>  >   would have its origin in white-collar workplace practices, I'll bet.

I am vaguely remembering something about miners receiving their pay
in an envelope with a piece of paper included with the money on which
was calculated the hours worked that week.  The paper was usually
white.  However, if the miner was being let go, the paper would be
pink.

Does anyone else remember hearing this?  Was it something I saw in a movie?

Rima