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LT3999 switch node voltage

Hi All,

I am using LT3999MP part in my design. As per datasheet, SW node voltages (at SWA and SWB) should be between -0.3V and 80V (screenshot below).

The transformer that I am using has leakage inductance of 0.45uH. Based on simulations with LT3999, I am observing ringing at the switch node during turn off and for brief amount of time during start-up (upto 5 msec), the switch node voltage goes below -0.3V up-to -6V. Will this damage the IC?

I am assuming that LT3999MP uses MOSFETs as switches and body diodes of MOSFET should have capability to handle this voltages. Please let me know if the device can sustain negative voltage spike of less than 10V for few msec during start-up or not?