Of all the words you might expect the BCG software to reject automatically, one of the very last you'd ever think of is surely "hum o rous" (without the spaces).
But just you try writing it without the spaces!
If you do, what you see in your post is "humourous" - a spelling considered wrong on both sides of the Atlantic.
Curious indeed.
But also rather humorous. 
P. S. It seems things have been this way for more than 10 years.
P. P. S for some reason, the system doesn't object to "tumorous".
