Saw this as a response to a similiar question on an Osteoporisis board:
"You should also check to make sure the vitamin D test you had checked your 25OHD level and not your 1,25OH2D level. The 1,25OH2D level has a higher normal range. If your 25OHD level was tested, it may be due to sun exposure. Otherwise, it is probably related to lab error, and will probably be lower when repeated."
I have had a doc order the wrong type of cortisol test before, and I ended up placed on prednisone and given a referral to an endocrinologist. Luckily, he realized immediately what happened and gave me a proper diagnosis. It's worth a phone call to make sure that the correct test was ordered.