LC Impedance Matching but gain larger than 0 dB

Dear all:

I studied the Chapter 2 of MW Transistor Amp by Gonzalez.
In Fig. 2.4.14 (p.130-132), the gain vo/vs > 0 dB (approximately 4 dB).
The impedance matching uses LC but no any active devices.
I try to calculate the gain by myself but still get the same result.
I understand something wrong, but I have no idea why...
Do anyone give me answer?
Thanks a lot.