Lehman was a symptom of a larger problem associated with mortgage backed securities, not a cause of the problem.
https://en.wikipedia.org/wiki/Collateralized_debt_obligation
The standardized, so-called "agency" MBS on the SVB books really isn't anything like that CDO plague. In 2008, people were losing faith in the ability to even assign valuations to CDOs; SVB's problem with their MBS portfolio is that the current market valuation is obviously not what they needed it to be just now.