i hope by now you have rectified the problem, mold can be dangerous depending on the type. but all molds are microscopic, every time you open and close a door the airflow will disperse the mold and it will travel. if it can find some where to hide it can cause ongoing problems, bathrooms are more susceptible because the environment is perfect for mold, old warm air flow systems that are not in use are a haven for mold once it is established. i have been a victim of mold. to the extent everything had to be destroyed in my flat, no matter how clean and tidy my flat was ,mold appeared every ware, i used every trick in the book to kill it, it took me years to find the problem that was causing it. what annoyed me more was i know how to kill mold it, was pat of my job. houses need to breath, they also need moister, dehumidifiers do not work, they will take years off your house, you need to drive the damp out, a good airflow and a constant temperature, mold will grow at 20 degrees Celsius and above. unfortunately we like to be at 20 degrees or above. mold needs moisture to grow. wipe down all wet surfaces and leave heater on and extractor fan on for abut 10 minutes after you use your bath room.alternatively if you have a window open it and allow airflow. window frames will condensate and cause mold to grow, make sure you wipe them down. get rid of any thing you can not clean inside and out, bathroom cabinets need to be sealed in side and out, plastic is ideal. most mold treatments do not kill mold they bleach it, it still there you just cant see it, that is why mold looks as if has traveled to new spot,almost every household has the best treatment for mold in there kitchen cupboard, vinegar, white is the best, dilute 1 vinegar to 5 warm water, use more than one cloth to remove the mold, leave for 24 hrs then rinse down it is that simple. if mold is in the grout between your tiles, then the wrong type of grout was applied, it is a laborious task to cut your grout out and re-grout but is very easy to do, you can buy a premixed mold resistant grout at any hardware store, the application instructions are easy to follow, getting out is awkward, a Stanley knife at a 45 degree angle from the tile edge either side, and a plastic pen case to get what the blade misses. do not worry if the blade leaves blacked lines on your tiles grout is an abrasive and will clean that off. sorry for the lengthy post, and i hope you have already killed your mold.