I didn't have anything like that with DS, but I did with DD. I got a little worried at first, but apparently it's quite normal. I was told it's more common to have a large clot after you have been sitting for a prolonged time. Rather than the blood slowly seeping out, it pools together and clots until you stand or push on the toilet.

I would also go a few days without blood-loss, and then have some bright red blood, but was told that that is also normal and it can just be like a "scab" tearing open a little :/ Weird.
Thanks That makes sense...DD has had me confined to the chair all day today because she is a booby monster....