Hi Philippe,

  

Handshake Protocol: Server Hello
[...]
Cipher Suite: TLS_RSA_WITH_AES_128_CBC_SHA (0x002f)

I don't see any DH here, so maybe that's not the problem.
    

I agree, it doesn't look like it's using DH. What would be interesting to 
see if you see a "Client key exchange" or a "Server key exchange" at the 
beginning of the SSL session in your capture when you look at it in 
Wireshark.

Also, you might want to use "-s 0" when running tcpdump, that just 
captures everything.