finishing high, or stuck fermentation?

A couple weeks ago I brewed up a batch of Orfy's Hob Goblin II and pitched some washed Nottingham that had been in my fridge for a couple months. I let it go, and the following evening the temp was getting kind of high, about 23-24C (~74-76F), so I put the carboy under an open window to cool off (it was about -5C that night, IIRC). The next morning the temperature had fallen by about 1 degree C, but visible signs of fermentation had stopped. I measured the gravity, and it was around 1.020-1.021. I figured it would come down a few points since I was only 36 hours in (the recipe's expected FG is 1.013).

From this point forward there have been no signs of fermentation, and the gravity hasn't changed (this was 10 days ago). So, I'm wondering if I should try to get the gravity down some more, or just bottle it?

The mash was pretty warm -- Calls for 69C (156F), and my temp held around 156-157 for the most part. The mash was also pretty thick (5.4kg/11.9lb of grain in 14qt of water), since I mash in a 5gal pot on my stovetop. For this reason I think I may just have a lot of complex sugars. My OG at pitching was 1.059 (expected in the recipe is 1.056). Pitched an 800ml starter, as I said, of washed Notty.

I'm not too concerned about the result -- it tastes quite good right now, though a bit sweet (and still pretty green), I just don't want to wind up with a bunch of extra fermentation going on after I bottle next week and causing explosions. So, do you guys think it's ok at 1.020, or should I pitch something more? (I stirred it up a bit after I took the gravity readings, both last week and tonight.)

Thanks!

since noones answered..ill put in my 2 cents.
"orfy's" acutal FG was 1.015. I dont know that 5 more points is worth your trouble. i would just enjoy the very slightly sweeter brew.

if you take grav, and 2 days later it still hasn't changed, it ain't going to. take it to a warmer place, swirling it a little bit as you do, and let it sit those 2 days, though. if still no change, bottle/keg

Ok, thanks guys. That's more or less what I figured, but a second opinion never hurts.