It's not normal but very likely anyone could get a misfire code on their vehicle. All that happened is that the Cylinder 4 ignition coil misfired or the computer got a bad signal once. I have had this come on every once in a while revving the engine up a little too much going to pass someone or the car getting a little squirrely in the rain. Most times you don't even notice it cause you're paying more attention to the road.

Even if the car needs a new ignition coil at 70,000+ is no reason to walk away from a sale. Especially if there were no other problems found. Parts fail, you never know when or where. Your talking about a $40 to $80 part.

Have them clear the code and then take it on a good 5-mile test drive. If it is the coil it will reappear as soon as you step on the gas a bit. Then it's just a simple repair especially on a 4 Cyl.

 

I would want to look at the #4 spark plug, which shouldn't be too much to ask, although by now they may have replaced the #4 plug.

Something like engine pinging or overheating could have melted/blasted away part of the center electrode, or there could be a problem with the plug being oil-fouled.

If it is spark-related, whether a bad plug or bad coil, the symptom will be worse when some combination of relatively cold spark plug and relatively high engine load occurs. So flooring it when the engine has had little time to warm up should show the symptom at it's worst.
But there is also the tendency for failing coils to produce insufficient voltage when they are hottest, after the engine has fully warmed up!
Of course, this being an automatic, the engine load will be lessened by a downshift, so a hard jab on the accelerator while applying some braking in first gear will load the engine best.

In-depth diagnostics might reveal under what conditions that the misfire occurred, pointing to an exact cause.

 

Thx for the replies. I asked the service manager at the time if the spark plugs were checked and he pointed to a checked box on the report that said "Ignition, starter, and accelerator" and he said the plugs were checked. But I didn't talk to the mechanic.

At the time I guessed Toyota engineers would allow some leeway for transient conditions before throwing a code. And there are some clues that this car hasn't been driven hard so I was surprised to see a code. I didn't want to risk buy into an electronics goose chase (that's why I'm getting rid of my current car).

But I think I did over react and probably should have just asked the seller to cover any necessary ignition system work.