I actually usually use that method to defrost a lot of meats that I cook especially chicken. It's not the best but it gets the job done usually.
To make sure your steak is medium rare the next time, if you have an instant read thermometer, you can measure the doneness of your steak by the temperature in middle of the thickest part of the steak. If it's medium rare, it should be around 54-57 Celsius.
Source: http://amazingribs.com/tips_and_technique/meat_temperature_guide.html