Should I Be Worried About The Delay In Taking Yasmin BC?

Question: I am on Yasmin BC. I was on it consistently for about two months and then I went off it for a month. I started back up about two months ago. But two weeks ago I went to London for a week and the hour at which I was taking the medicine was six hours off. I have not missed any pills but since then I have taken the pill within a four or five hour time variation. I had sex without a condom. Should I be worried?