Yaris Gearbox gear change problem?

[slnko2003]

Just bought a Yaris 30K On clock
2004
Semi Auto
1 Litre

When the car changes gear in auto the engine revs die for a moment before the higher gear engages and then the engine speeds up.
The garage owner told me this was normal for Yaris.
My boyfriend says no it must be a clutch actuator issue?
Could be quite dangerous when you need speed quickly.

Is this normal for a Toyota Yaris Semi -Automatic?

Thanks for any replies

Lydia