Yep - I agree! Call them for sure.
But I have to say - I had a bit of bleeding in my first few weeks with Marieke, but it took a couple of blood tests to figure out that everything was fine. They had to make sure that the levels were still going up, so they had to take blood one day, and then again a day or two later. But everything was fine - hopefully yours will be the same! (mine ended up being my cervix bleeding after DTD. Nothing a few days "rest" wouldn't fix! )
All the best!