u should just know i never got a 1099 for aa miles from last year or 2 yrs ago
Nitantnel is correct that they are taxable but the IRS is not strict about it. They haven't made a decision how to mandate it, but don't worry when they do, it will work prospectively, so no one that hasn't reported their miles or points will be in trouble.
Now if your bank gives you a 1099 it gets more complicated because now it is reported to the IRS. There is a lot on this, but in short they will usually give you a 1099 only if it's a cash back reward, like in the OP's case. (If you get a 1099 you should be reporting it)
There was a case where a business owner collected a lot of points from his business card and bought an expensive car with it (you can only imagine how many points he accumulated). He had to pay taxes on it and I think the bank gave him a 1099 on the car.