Is it something to worry about? The spot has been there a few months, it is not soft or mushy. It does not show on the top of the leaf and it hasn't grown or changed shape.
At first glance I would have said cut it off immediately. However, if it has been there and not grown in months and not mushy or soft then I would have to think about it longer. I want to hear what others with more experience would do. I probably would cut it off if it bothered me aesthetically and then sprinkle the cut with cinnamon powder.
Think I am with Swamper on this one I would cut it off.....its a nasty looking stuff and you never know for sure what it may do in the future might need a long time to mature and shed spores? But it could be Chemical damage too and not fungal at all...just hard to tell for me...but I think cutting that leaf tip off would serve two functions -
1 no more what ever it is and no chance of spores.
2 I think it would look better
Oh and if you dont want it looking like it was cut off there is no reason you can not cut it carefully from both sides to a rounded tip and dust with cinnamon ...
THe cut does not have to be straight across and make it look damaged.