Battersea Power Station said:
No, not saying that. But they lead us to believe he was in a conundrum with no way out, when it turned out there was some seemingly basic thing he could've done that everyone knew about, yet acted upset/borderline surprised when he whipped it out.
The trick with this is that a) Tyrion didn't really think that Bronn would come to rescue him, he did it as a last resort. Also, he had seen Bronn fight but didn't know how good of a fighter he would be. Tyrion also, IIRC, makes quite a show about mentioning how Lannisters pay their debts in a place where Bronn can hear, knowing Bronn to be a sell sword.
It's surprising because: b) Nobody in the Eyrie knows that Bronn is sympathetic to Tyrion, not even Catelyn. She seems them joking with each other but beyond that, nothing more. Further, Lysa accepts the trial by combat because she unwittingly thinks that he has no chance: THe Imp can't defeat anybody in combat and his only champion is thousands of miles away... When Lysa accepts that he should have a champion, it's assumed to be Jaime, and she thinks she's outsmarting Tyrion by offering up Jaime. In the Book, Catelyn doubts how wise her sister is, and if I remember correctly, knows that Tyrion is up to something immediately, but can't do much to step in.
FINALLY, is c) It is stressed in the book that if Tyrion does somehow win this fight, he'll have no chance to survive outside the Vale of Arryn. It's surrounded by mountain crazies who are completely mad. So even with Tyrion winning, Lysa doesn't worry all that much about it, knowing that Tyrion will have no chance of survival outside of the Vale.
In short, Lysa really comes away as being a total fool in the whole exchange.
