I have located this stamp in the Scott catalogue and determined that it is Scott #43, however I do not know why there is a black border!

Was this put on by the stamp printer or after the fact? It looks like the postmark was placed after the black border! I understand that envelopes were bordered in black when they related to a death.
If this is an official version then does it have a different Scott number?
Thanks for any help that can be provided.
- stamporator -