courtesy checks are mainly for them to find something else for you to pay for, and sometimes they might make it sound worse than it really is.
one time i took my tacoma in for a recall on clutch squeeking and they told me i only had a few thousand left on my brake pads and shoes (i was around 45k miles). i said thanks and bought pads and shoes myself, took it to school to use the lift, took the tires off and looked at the pads and shoes, and there was like 6/32 all around, which should last a lot more than a few thousand. since i had already gotten what i needed and the truck was in the air anyway, i just put the new ones on for experience.