as long as you take one pill per day (if it is a combined pill) then you are protected. if it is more than 12 hours late it is considered missed.
basically, if you do not take a pill for 1-2 days, it allows the hormones in your body to drop low enough to possibly release an egg. How likely is it that this will happen? it is according to your body.
if you ingested hormones once every two hours, then you are ok. if you did not ingest hormones for one period of 12 hours, then it means you missed a pill.
technically speaking, since you took your pills monday night/morning (correct?) then you only missed one dose