Finished BC Pack, had sex, bled like crazy?

[behatiboo.livejournal.com]

Hi, can someone give some insight on what happened to me last night? I had just finished my 2nd pill pack yesterday of Minastrin. I've been on BCP for about 3 years and had to change from Lo Loestrin to Minastrin. I start my third pack of Minastrin on Friday. I had sex last night and went to the bathroom afterwards to clean up and there was bright red blood all over my legs. I thought I just got my period early but after about an hour of bleeding, it stopped. I have stopped bleeding and I should be getting my period on Wednesday. Should I be concerned or is it normal to bleed like this when expecting your period and you have sex?