Shedding uterine tissue?!

[demonic-force13.livejournal.com]

My period has been giving me a lot of problems lately, and when I went to the bathroom this morning I saw what I thought was a huge blood clot on my pad. But when I rinsed the pad off(I use cloth pads) I noticed that it was actually a pinkish/reddish piece of tissue. It was maybe an inch long and not very thick. It didn't smell funny and I'm not in any unusual pain, but I'm freaking out! Is it normal to shed tissue during your period or should I see a dr? I've never had this happen before.