Unbelievable/Blood Work

My dad went today to see his oncologist. My parents moved to a new town last year around this time and have had two different oncologist this past year. He has been on vextibux and campostar since June 2007 (cea went from 128 to 14 in September 2007). It was done once a month around the 5th -10th). The last cea taken in September was 14.8. His ct scan showed stable liver mets (one grew) and lung mets that had shrunk. Doc switched drugs beginning at the end of September (5 fl and erbitrux instead of vextibux). The nurse was supposed to take blood for the cea test on October 12 (forgot). Took blood on October 15 instead. Well, mom called in on Wednesday (10/17) and nurse said most recent was 16.8. So, they go to for their monthly appointment with the oncologist today and he says the cea is 131. Unbelievable!! What happened?? His cea was 14.8 when the ct scan showed stable liver mets and shrinking lung mets (September 19). We are not sure what the deal is. The oncologist is redoing the blood work today. I know that the cea is not a marker for everybody but it is for my dad (many oncologists have said so). Thank god we have an appointment at Hopkins on Tuesday, October 23. Any thoughts??

Has anyone had their blood work screwed up before like this??