Under normal conditions, there should be no undershoot when MAX8902 turns on. The startup waveform can be seen on page 4 of the datasheet (rev 6 1/15) and is also shown below. The 200mV undershoot is possibly due to the load at the output. However, as long as the undershoot does not go beyond -300mV (absolute maximum rating as mentioned in the data sheet), it will not affect the chip operation, and will not damage the chip.