No, it won't hurt anything. The C rating in this context indicates what the lipo is supposed to be capable of discharging. A 4000mah 25C would be expected to discharge 4000/1000 x 25 = 100amps, similarly, a 30C would be 120amps.

A battery doesn't force current thru a setup - the motor is what sets the amp demand, the esc responds to what the motor needs. A 30C vs a 25C isn't going to hurt anything. The 30C will have a little smaller voltage drop at load than the 25C would. More battery that you need? Probably, but that is how most setups are run. That helps keep things cool.

If you were flying a plane, it would be diff - higher C rated lipos tend to weigh a little more, here is a surface rc is isn't that much of an issue like it is in a elec plane.