Higher than expected FG

I have a split 10 gallon batch of IPA that was in primary for 7 days. It has been in secondary for 3 days now and is settling out nicely. I fermented one batch on WY American Ale Blend and the other on Ringwood just for a little experiment. I have used both of these yeasts before on similar IPA's and have had FG in the 1.012 range. Both of these IPA seem to be done at 1.018. What would cause this??

Both batches used healthy yeast starters made from second or third generation yeast that had been washed and harvested. OG was 1.064.

Thanks

Alan

Extract or AG? If AG, did you hit your mash temps or come in a little high?

AG, mash temp 156, dropped a degree or two in the last 15 minutes.

Was it the same mash temp as the other IPAs. Ringwood is highly flocculate so you might have to re-suspend it to get it to finish lower. Your yeast might of mutated and attenutation might not be that high. There is a lot of factors that can affect attentuation like concentration of yeast, o2 levels, etc but because both finished at that level it might just be your mash temps