Blue images

My wife has been using several SanDisk micro SD cards and an Olympus XD whilst photographing in the Philippines using an Olympus Tough. On some of the cards all the images have come out blue;  on another card images at the begining have come out blue, while those at the end are normal; on other cards the images are normal. Previous images have all been normal, using this camera and the same cards in the Philippines. Could high temperatures or high humidity cause this? The camera was set in on auto white balance in all cases as my wife does not know how to change this - so could not have done it accidently.