"There is a second respect in which we must beware of being misled by the traditional account associating backshift with indirect reported speech. ...
Converting into indirect reported speech, ..., is not a matter of applying rules of grammar that are specific to this purpose.
ii [Original] I broke it.
[Backshifted] She said that she had broken it.
[Non-backshifted] She said that she broke it.
[The Cambridge Grammar of the English Language (CGEL), p154-155]
I'd say that both your example and your colleague's example are fine, but though your colleague's example reports the speech, I think the extra 'had' adds a greater dimension to the response. More on this later.
Let's forget Louise's question for now and look at what you might have said;
Lupuspol: I had a good trip / That was a good trip 
Bill: How was Lupuspol's trip?
Jane: He said he had a good trip. // He said he had had a good trip.
 ["I've had a good trip" - also possible but I think it's severely restrained by time considerations; deal with this later or in another thread]