Spring throws JpaSystemException when using Hibernate Validator

[FkJ]

When I use Hibernate Validator (3.1.0 + 3.3.1 Core) with Spring (2.5.6) I can't catch the InvalidStateException directly. Spring throws a JpaSystemException, whose cause is a RollBackException, whose cause is finally the InvalidStateException. The same happens with PersistenceException and IllegalArgumentException at methods that I have implemented, like the following example:

        @PrePersist
        @PreUpdate
        protected void prePersist(StReservaVeiculo reserva)
        {
            if(reserva.getKmInicial() != null && reserva.getKmFinal() != null &&
                reserva.getKmInicial() > reserva.getKmFinal())
            {
                throw new PersistenceException("KM inicial maior que KM final");
            }       
        }

DAO:

      @Transactional(readOnly = false, propagation = Propagation.REQUIRED)
        public void persist(T t)
        {
           em.merge(t);
        }

If add a call to EntityManager's flush() after merge(), I get the expected result, so I can catch the exceptions normally.

Is this the best approach?

Thanks,
Felipe

[FkJ]

...
Anyone?