If I may get wonky here for a moment, let me give you the banker's point of view.
By definition a portfolio loan does not get sold, the term means the lender holds it in their own 'portfolio'. The term portfolio lender or not isn't the whole story. A loan is a portfolio loan or it isn't but that doesn't mean all loans the lender does are one way or the other. More specifically you'll hear things like on balance sheet (portfolio) or off balance sheet (sold to a third party) financing.
As a banker I can bore you with more details if you want, but I think the big take away is to learn to understand the jargon. The reason is that if you understand the terms being used, you can understand if something is in or out of context. Nothing screams professional more than someone who understands the lexicon and then negotiates using that information.
For people who listen to the BP podcast, you've probably heard (and I can confirm) that professionalism matters a great deal in the lending process.
Right, wrong or indifferent, the facts are that if you know the secret handshake of any club, you're more likely going to get a warm reception from that club. Knowing how banks operate and the context of terms you're negotiating goes a long way.