steam smoke from Yam 50hp 4 st

[lffoar44]

Hi all,
Just a query 'cos there seems to be a lot of opinions on the net.
My Yammy 50hp 4 stroke runs well, has had the impeller replaced recently and has a strong pee of water at any revs.
I notice a wisp of steam smoke at the back of the motor at times. Nothing excessive and as I say, the motor is running great. Is this normal or something I should get my knickers in a twist about?

[boats.net]

If it's coming out the exhaust relief hole in back probably nothing to worry about.