Dextrose Cause Super Low FG?

My latest brew, an IIPA is just finishing up and it is the lowest FG I've ever had. I had an OG of 1.080 and an FG of 1.007. To me that seems too low but I am wondering if the sugar is adding so much alcohol that it is lowing the FG that much more than normal.

Here is what I did (adaptation of BCS IIPA):

30 lb 2-Row
1.5 lb Crystal 40L
1 lb Wheat Malt
3 lb Dextrose

Mash 149F 60 Minutes
Pre Boil (no sugar added) - 56L (14.8 gal) @ 1.063
Post Boil (with sugar) - 52.7L (13.9 gal) @ 1.080

I used 500mL of 1056 yeast harvested 2 days before and O2 of 90 seconds @ 1L/min for each fermentor ~5.5 gal.

I fermented at 65F for the first 10 days and then ramped up to 70F to finish it off.

12 days later I'm down at 1.007 as measured by digital refractometer AND calibrated, temperature adjusted hydrometer. Everything tastes great and I've added the dry hops now so I don't think it's a wild yeast or an infection (knock on wood). Normally I can get down to 1.010 and have pretty fermentable wort with the O2 and the HERMS but this seems crazy. Is it the sugar or should I be worried?

That sounds about right really, dextrose gives 44-45 ppg, you're hitting around 9-10% of your fermentable sugar from the dextrose and 1056 is a high attenuator.

It seems a bit low, but I could see the sugar drying it out to that point, particularly if you had excellent efficiency. Sounds like you should be pleased . I wouldn't worry unless it was getting a peculiar taste, at this point.

I was just trying to hit the style. I'll just add enough hops for the mouthfeel. It seems like with my system I need to mash a little higher.