That's an odd one because I post to the SharePoint forums all the time and I never noticed it.
I did now (!) when posting this message - you mean the fact that there's a dotted red line below the word SharePoint presumably.
Yes, it would be a good idea to get rid of that.
The choice then would be whether the (wrong) alternatives Sharepoint and sharepoint would then be included in the dictionary as well. I'd prefer not - i.e. that SharePoint is the only accepted spelling !!