Fix cacheing problem with findRoot in SigETransform

Plots post-fix attached

![seoe_lead_ee_fix](https://cloud.githubusercontent.com/assets/638761/3026376/fe4758ce-e013-11e3-9248-510cbbdabf7e.png)
![seoe_lead_eb_fix](https://cloud.githubusercontent.com/assets/638761/3026377/fe562778-e013-11e3-938c-1fa8c1a76e4a.png)