...the car? Even if only once? I have only done it once, and i added about 7 gallons of it. I believe there was about a little less then a quarter tank of premium left in it.

You should always use the recommended grade of gas. Using a higher or lower grade of gas can reduce horsepower, fuel economy, and in extreme cases cause engine damage.

If the recommended grade is not available then it is best to error to the next higher grade. If for example your car requires the middle grade and it's not available put in the premium. If your car requires the highest grade of gas and all you can get is medium then put in medium, but only enough to get you around till you can fill up with the proper fuel.

It's a pain in the butt but when I'm at the cabin in northern Wisconsin I have to drive 20 minutes for premium gas, or 5 minutes for regular gas. I don't like driving an extra 15 min one way to get the proper fuel, but I'd like replacing an engine even less!

In short, you most likely didn't hurt your car, but why tempt fate? If it costs you $0.10 more per gallon for premium that's only $1 on a 10 Gal. tank in your Acura. If you can't afford $1 extra for good gas you can't afford an Acura.

If you did not have valve train rattle with the regular gas. It will be fine in your engine.

The only thing the octane does is keep the upper engine from chattering or pinging.

If you filled up with just normal over premium time after time. Then you might cause damage only in the form of lower horsepower, wasted gas and carbon build up. But to actually "harm" it. No.