No symptoms, what would be a reason to change Brake Booster & Master cylinder?

I didn't get it done yet. I was told that the master cylinder was leaking into the brake booster. The reason I asked the question in that manner is because I am trying to find out if anyone had heard of a reason to change these parts when there is no problem. I was told that this problem is because I am not driving the truck enough. It only has 37, 500 miles on it.

Ok, that is definitely a possibility and a good reason to replace the parts .. Brake fluid from leaking master cylinder may have damaged the booster as well .. I was thinking it had been done for no obvious reason... 'Sometimes' that will cause smoke from exhaust IF enough fluid gets in the booster and is pulled into the engine through the vacuum hose when applying brakes ... That is pretty low mileage on a 2009 for sure!

Thank you for your response. Now I feel a little better about spending $500 on a problem I can see no evidence of. Thanks.