When I start my Briggs 11 HP on a riding mower, I get a big puff of white smoke... then
It stops smoking and runs fine. It starts easily and runs great after that puff.

Sounds like its got some years on it.

Personally unless it was new... I wouldn't worry.

Worn valve guides and possible worn/sticking oil control rings

Hi,
Personally, it probably does have some age, but it is normal.
Peace,
Clarke