Accidentally switched two of my birth control pills?

My boyfriend and I experienced a torn condom during a long and energetic interlude; I wasn't overly concerned until I went to take my birth control pill the following night and realized that I had accidentally taken the pill for day 20 and day 19. I took pills 19 and 21 together, but am worried that the disruption could have made me vulnerable to pregnancy, especially since this is my first month on BC. Need I be worried?