No disrespect dudeman, but without pictures, how can you tell him this is "normal"?
I would recommend the brake pistons are not frozen or pitted and be certain the studs are tightened down correctly, i.e. mount bolts, etc. Sometimes the bracket bolts get loose or are broken and still look OK!
This means removing the calipers, mounts, lines; and having a close look at what's going on in there.
If the caliper pins are bent, rusted, full of crud, un-lubricated with high temperature grease, or had broken rubber pin-boots; the caliper could not slide the assembly, PROPERLY.
The piston may NOT be stuck or pitted, however it would push only 1 side of the pad to the disk, wearing the pads badly in the shape of the restricted pin movement, or as a wedge. (The un-stuck side, naturally would wear first).
Bent or frozen slide-pins will do this, especially if the calipers have been repeatedly pushed back. (Un-bent brake bolts, (or pins), lubed with NAPA High temp BRAKE GREASE, protected by new rubber seals would be cool, right?)
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I would recommend you rebuild / replace the calipers, just to be sure it is safe, unless they have only been re-padded 1 time. You can usually get 1 push out of the fronts, as they wear faster. Rears might be bad the first re-build, as they wear slowly and get crud int the system over time.
There is no reason to grind the disks, "IF they are within spec".
Dial indicator time. Measure it to be safe.
Swedish engineers agree, there is no reason to re-grind a rotor surface which is not warped, grooved or gouged. (Only US mnfgr's "require' this stupidity, go figure). Ask any Volvo repairman; Volvo does not recommend re-surfacing, as it is a waste of money and grinds good surfaces, for nothing. Replacement pads re-grind the disk true, just as well as a machine tool, unless they are warped or show signs of checking. You must measure rotor thickness, to be sure. (Check the knowledge-base for the correct spec.)
You'll know it, if you see checking. It looks like the disk is cracked or was quenched while very hot, in cold water. They may look blue, from the uneven wear, as well. Blue / Orange coloring is bad and the steel might be tempered and will wear out new pads fast or squeal.
You can push back the pistons once, maybe twice if they are OEM or rebuilt by a quality American / Japanese / German manufacturer, (Maybe Mexico) and only if they did NOT grind into the disk.
Unless you have personally done all the repairs yourself and know which manufacturer the calipers are from, you're going to want new OEM or better parts that MATCH.
Not all discount auto suppliers sell OEM spec brake parts. in fact, it is getting worse.
The quality and piston seals / tolerances can be thousandths off spec., differing widely between manufacturers, (and that's why some suppliers do not charge for core, ((too far to ship back)), and why the big brakes are a better choice than after-market slugs from China).
By using one new caliper, from one mnfgr. and another from somewhere else, your braking may be incorrectly proportioned and cause uneven pad-wear, too. Heck, we all have had to perform a quick fix to save a buck, but make sure you understand the consequences.
Metallurgy, nickel / carbon content, makes a huge difference as to how the calipers and rotors perform and last.
Cheap rotors warp really fast, during the first rain storm, on a day you have been driving hard and hit 1 single puddle. All the money you save, is gone when they warp and glaze, using cheap parts. (Yes, the expensive ones can glaze too).
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If it looks like something is "very wrong", don't take a chance with your life or someone else's. With brakes, you get what you pay for. Spend the time to research and find quality parts and you'll often save yourself the hassle of doing the job twice.
If you are building a high HP engine, don't consider bolting on, one single part until the brakes are 100% safe. Stopping=good!