I am used to it - with cold oil and using a '95 Yamaha XJ 600 S. After a few km only one single sound of the »aftershock«. A few km more (10+), all works fine.
So it is not something that will destroy the clutch nor the gearbox in the next few km of riding the machine. But it does not sound very nice.
* Does the problem occur also after 20 km riding or just after the start?
* Have you had it always or did it appear suddenly after 20'000 km (or sth like that) out of nowhere?
Greetings, Martin