I did a search but couldn't find any answer.....so my 2 year old battery died yesterday, I got a replacement, but I went to auto-zone to test the alternator just to make sure. They told me that the alternator failed the test because is only producing 13.3-13.5 v. My question is, 13.3v normal for this car? or the alternator is really not producing enough voltage?

 

for 2007 (or I expect any of the 2nd gen), is350/is250, without load normal voltage on the generator should be 13.2-14.8 volts. Test without load is running the car @ 2000 rpm. There should be 10A or less running to the generator.
With load (hi beams on, heater on full) there should be 30A or more on the generator if the battery is NOT fully charged. If it is fully charged there could be less that 30A. Manual doesn't give a voltage with load, so I'd expect 13.2-14.8V.
This is not to say your alternator is fine, but I'd get a second opinion.

 

It is definitely on the lower-end of the acceptable range. I would spend the $160 (AutoZone lifetime warrantied reman replacement) to replace it so it doesn't leave you stranded.