How did my efficiency get so high?

I did my third AG batch yesterday. My previous 2 batches i averaged 70-71 % efficiency so I figured that into my recipe. My preboil gravity was sopposed to be 1.041 and It was 1.046 when I put that number in the program it said I was at 80% efficiency. I'm batch sparging and the first 2 batches i sparged with 170 degree water I didnt realize i was sopposed to bring the grain bed temp up to 170. This time I batch sparged with 178 degree water. Would this alone cause my efficiency to jump 9-10 %?

Thanks James

It's possible. The higher temps could have rinsed more sugars from the grains. Effienciency can be changed by a number of factors though, most often crush level. If you used a different type of base malt, or it was fresher or more properly crushed, these could have also effected your efficiency.