I've been on it for 5 months now. Spotted, not heavy like my normal period, the ENTIRE first month. Then it stopped-the doctor, who I trust and is very good, says spotting is totally normal and every woman reacts differently. Recently I started spotting again, with even small clots after sex, and I believe the other posts are correct-I used to take it at EXACTLY the same time every night, but recently have been late just a few hours some nights. My doctor said this is probably why I am spotting again, and if I go back to being rigid about taking it at the same time, spotting will stop.
The spotting experiences posted here seem like normal adjustment to Seasonique based on everything my doc told me, but I'm not a doctor. If you're really concerned, (and usually you know in your gut when something's wrong) go get a checkup. Health isn't something you should ignore. You're messing with your hormones and occasional bleeding is normal, which may make you more easily ignore the signs that something is really wrong.