Every time I think I have a good comment, I find someone has beaten me to it!
My brazilian friends told me that, when in english we say "I have a problem", in portuguese we say "eu estou com um problema". I used to say "Eu tenho um problema" but now I don't say it anymore because they told me it wasn't really the way they speak.
SO, it's not a mistake but I had to tell you this :-)
It's actually correct, in European Portuguese, that's exactly what we say. You are absolutly right :)