After started up the engine, the rpm gauge first drops below normal idle rpm.

What is your question?

After started up the engine, the rpm gauge initially drops to about 600 rpm, then recovers to the normal idle rpm of about 900 rpm. what causes this hesitation? Note: the engine started up right the way without any rattling or difficulties; the spark plugs and wires are new as well as air filter, fuel filter and fuel pump. thank you for prompt responses