I think that it is the sign of a very dedicated practioner to try to say mantras and listen to teaching whenever and where ever they are. You certainly should be satisfied that your mind is turned towards the Dharma. I once asked my Tsawai Lama, Drikung Lamchen Rinpoche the same type of question and his reply was that while it is always good to have your mind turned towwards the Dharma, and always good to be saying mantra, that mantras said out of context of doing your Dharma practice, that is while you are practicing and have gone through the dedication process and are conscious of what you are saying and your visualization is stable, cannot be counted towards mantra accumulation for ngondro practice or any situation where you are attempting to accumulate mantras to fulfil a requirement of your guru's instruction. However, wouldn; it be great if we all went through our daily life saying our mantra instead of engaging in idle speech? Hooray for you and may we all take that as an example of dedicated Dharma practioners!