When Fredo "met" Johnny Ola at the party, Fredo looked stricken with terror...he didn't know how to handle the introduction. It was Ola who bluffed through it, and Fredo followed his lead.
I agree. But I disagree with any opinion that Michael suspected Fredo of knowing Ola or Roth. When Fredo arrives at the hotel, it is he who brings up the subject about knowing anyone in Havana. However, it is somewhat strange that Fredo seems to already be familiar with Havana: "It's my kind of town." he tells Michael. Despite his recent arrival, he seems to already be familiar with local drinks. At the nightclub, he suggests some local drinks to Geary et al.
