I started pumping at the same time as you with the same pump too. I get the same messages sometimes about 'can't guarantee accuracy', but when I've checked the pump data it is all OK - I just check it every time I get the message, maybe 3 or 4 times now. I was worried at first, maybe I'm a bit too blase about it now! Why don't you ring the help line at Accuchek to put your mind at rest, I always speak to really knowlegeable and helpful people - I have rung them quite a few times!
(I still love te bluetooth, don't think I'd've been up for a pump at all if I couldn't do it this way, I didn't want to have to keep removing the pump from under layers of clothes!)