Thanks for the feedback OP, good for you. That’s the best way to learn diy’er auto repair, have it shown to you by a pro the first time. That’s the way physicians learn their trade too. The have a saying “watch it done by someone experienced the first time, do it under supervision of someone experienced the second time, and show how it is done to a newbie the third time”.
If the mechanic didn’t connect it to a computer test, he was no mechanic.But, if you have someone to install them, take advantage. For my car, it lasted over 70K without a change. But if I had someone to change them at 60K mi, considering on average it would cost somewhere in the range of $200, regardless, there is peace of mind, knowing that you have one less worry. And anything not under warranty, brand new or not, can go at the drop of a hat.