Can nonspecific white matter changes for a healthy looking 35 yo male that doesn't manifest neurological symptoms (and without migraine) possibly be an early sign of demyelinating disease?

The answer is cautiously yes but bear in mind that there needs to be clinical correlation. Those changes are nonsignificant if the patient has no correlating symptoms. Other potential causes for those findings could include hypertension and arrhythmia such as atrial fibrillation and these should be evaluated for as well.

If he is apparently healthy, why would imaging have been done? But non diagnostic white matter lesions must fulfill McDonald criteria to confirm MS. Some miscellaneous causes of T2 lesions, cigarette smoking, some medications, prior head trauma, genetic disorders, early microvascular angiopathy.