I have been playing New Vegas for a good while now, and have bought all DLC available. So the base game level cap is 30, with 5 added per DLC right? So that means my level cap should be 45? And I should not be able to get any higher. Yet I reached level 50 today.. I was wondering what happened.. And am I a single account of this or has anyone else done so?

The recent patch v1.6 introduced this, specifically on PS3, as several others have noticed already.
Some searching will help you finding other threads on the subject.
Cheers!

I have the same problem, I stopped playing my main file just in case I miss any good LR perks, but my question is, will they now make LR go to 55???

I have this problem. I'm hoping we get a separate patch soon. Right now I am at level 47, trying not to level up. This svcks

I'm right there with ya
They're going to be sending out another patch for LR that will make OWB better too, so lets hope they fix it then