Poor eff. on hefe today, help

hey guys, we brewed a hefe today that consisted of 6 pounds of white wheat malt, 2 pounds of 2 row, and a half pound of flaked barley. Mashed in with a 1.25 grain to water ratio at 153 degrees. I've been getting 80 percent eff. on my setup but today something went terribly wrong. We ended up with a 1.040 instead of the target 1.052. Ended up around 60 percent eff. Its been awhile since we have had any kind of problem like that. Everything seemed to go perfect on the brew day which kinda shocked us on how much we missed our target OG by. The only thing that went wrong is that I forgot to add rice hulls to the mash, so I added them at the end of the 60 minutes before I started to sparge. Any ideas on why we missed our gravity by so much? Thanks for any info.

Are you confident in your readings, instruments, etc.? For your initial gravity reading, did you adjust for temperature? Adding the rice hulls won't affect the gravity; they are only used to assist in lautering. Did you have any lautering issues, stuck mash?

no issues at all, sparges went perfect.