It is a common "problem" that really is not a problem at all! It means the sensors on your detector are working properly. The first smoke that comes off of a fire is moisture burning off. (that is why a fire smokes white/pale grey but the smoke gets darker as the fire burns hotter but then once firefighters attack the blaze with their hoses, the smoke returns to the pale color but thicker) Your detector was designed to go off upon early detection of a threat, which is mimicked by the bath steam in nearly every manner.