precuts are (generally) not pre-washed- but if the colors are deep/saturated you might want to at least color test them before using- (wet- rub with paper towel/piece of muslin-if color comes off you have a bleeder & may want to wash it)
the problem with pre-washing pre-cuts is the distortion/shrinkage- you may start with 10" squares and have something else after- but it boils down to your choice- there are some people who pre-wash every single fabric they purchase (& tend to stay away from pre-cuts) and there are those who prewash nothing....
the pattern you are using may also play a role in the decision- if you need accurate 10" squares you may not want to pre-wash- if cutting them up & have some *fudge-room* it won't matter so much...but at least test for color run