If I have elevated MCV and MCH but normal hct and hgb, what does it mean?

Abnormal labwork. It may not necessarily mean anything as far as you having any disease. It is more important to know why the test was done (symptoms for example). The measurements you referred to involve red blood cells and indicate that there there is increased mean corpuscular volume and hemoglobin weight. Those are seen in certain anemias and vitamin deficiencies, such as Folic Acid or b12, iron and hypoxia.
Some ideas. This may be due to something as simple as a cold agglutinin that causes the machine to misread two cells as one. If the MCV is below 100, i'd ignore it; if there's any reason to suspect you are B12 or folate (folic acid) deficient, hypothyroid or drink a lot of alcohol, please address these possibilities.