The hymen is a piece of tissue inside the vagina that typically rips during the first time you have sex. It can, and often does, rip long before this- but not always. SO anything from no blood at all to what seems like a LOT can be pretty normal. It's also not impossible for the next time or two to also have a little bit of blood, stretching, and even pain. Unless you start feeling lots of pain and cramping, feel faint, or bleed through a pad/tampon in less than an hour you don't have anything to worry about.
It is possible because that was your first time.