Any potential insult would go right over Cal's head. He hears worse all the time.

He hesitates, then says,

"I was just thinking -"

He's not sure what he was thinking at this point. He went over it so many times in his head during the movie that he no longer knows what was there and what he made up, if he ever knew in the first place, and he hasn't gotten any closer to deciding whether it's best to bring it up or leave it alone.