Depends on your application really, with s11= -11dB, that tells you that approx 10% of input power was reflected. with the resonance at 2.35GHz, if, with the same configuration s11=-10dB, it still indicates that at 2.4GHz 10% of power reflected. Ideally, you'd try to centralise your resonant frequency at the frequency of interest, because standard patch antennas are notoriously narrow band. Having said that, there are also methods to increase bandwidth of patch antennas, like slotted patches.