I got admited to a PhD program without a master degree. Does it hurt when I apply for a postdoc? I am a graduate student in Sweden, and will present my PhD thesis next semester, and have several articles accepted/published.

However, when I applied (and got admitted) I had only studied at the university for three years, and only written a bachelors thesis. Me being admitted was sort of an "error" from the department, (and I had no idea what really was the requirements, since my thesis advisor encouraged me to apply). 

Might this look bad on my resumé when applying for a post-doc position?
(Or is young age an advantage, in my case, 25)?

Edit: To follow up, I am now 32 and not as young anymore. I had no big issues finding post-doc positions, and I am still in academia.
In most places I know (Europe mostly, France and UK in particular), a Master's degree is nothing more than a tiny blip on your CV by the time you have a successful PhD (diploma, publication, good recommendations, involved in your community, …). Your lack of a Master’s degree will not hurt one bit (but it probably will come up in an interview, so you want to have something decent or funny to say about it). I suspect the same will be true in most places: by the time you are a post-doc, Master's degree is not a good predictor of your future success.

Regarding age, it's a very good question, and should probably be separate. As a post-doc, it shouldn't hurt your chances (I defended my PhD at the same age you are, so I have given it some thought!). For a staff position, things are very different.