No, they could have thrush which is a yeast infection of the mouth or it could be plaque, but before you do anything you should both get tested to be positive that way you do not end up in trouble later on!
If A Person Has A White Tongue, Does It Mean They Have HIV?
No it doesnt. Its one of the signs but does not mean yes. The only way you no for sure is getting tested worry your self to death about every little system is not a way to live.