I don't think he was being dishonest but I do think he is insincere. If I don't know if your stories are true or not and it doesn't matter why even say it? He was trying to be nice to you but he also had to consider that Rifke was going to read it. And he avoided saying that you might make up stories bu making it indirect. "I don't know if you're making up stories" vs "I don't know what's true and what's not."He was being honest.
It's the same thing but it's crafted to sound a different way. He's a lot like another poster here in that way. Really interested in how things sound and trying to please all the people all the time.
So he's not dishonest. He's just not being sincere.
Then the whole "peace be upon you" thing sounds familiar, too.