Aug 2015: Non-minimal cutsets using Simple Quantitative 
It is possible to generate non-minimal cutsets when:
1) You use the “Log. and simple quant.” setting in the analysis.
2) You have negated basic events or use NAND or NOR gates in the fault tree structure.
The problem only occurs when a MCS includes negated events. It has to do with the way RSAT propagate a MCS to verify that it is valid. 
You can remove non-minimal cutsets by using the additional minimization step after the cutset generation (check the 'Always perform forced minimization' in Analysis Settings). 
Fixed in 3.3.0 
RiskSpectrum Analysis Tools (RSAT)