Fermentation too fast?

[ChopperHarris]

I am having a first stab at malt extract brew, trying a pale ale.
I made a mistake with the temperature of the mash, which was too high. About 78 degrees. Everything else seemed to go to plan.
The starting gravity was 1058, the fermentation started well enough, but the bubbles have stopped after 2 days. I just took a gravity reading, which is 1012. This seems very quick to get to that level. Do you think I should leave it or add more yeast?

 

[Clint]

You sure you got it right....mashing malt extract?

 

[ChopperHarris]

Sorry, should have said. Used DME for the boil, but prior to that I used 100g of crystal malt in a 30 min Mash. Should have been 65 degrees not 78

 

[Dexter101]

100g grams crystal is unlikely to make massive difference i would guess...

mashing too high would either lead to no sugars being converted as enzymes would denature or if not that high the longer chains (beta amylase?!) Would result in higher final og

take another reading tomorrow and if its still the same i would have thought that would be fine. 1012 is a reasonable fg to my mind.