findAndModify operations which do not exceed the slowms threshold will always be absent from the system.profile collection.

This is happening because FindAndModify::run() is failing to call CurOp::enter_inlock(). The enter_inlock is responsible for raising the profiling level associated with the operation, based on the database profiling level. Failing to call it means that the operation's profiling level is erroneously left as "0".