First of all, synth3tik is incorrect--although matched pairs gives a speed boost to the MacBook, and a very slight boost to an MBP, both will recognize unmatched pairs just fine.
That said, I'm not sure I'm following your question; you're saying that the MBP came with one 512MB stick as opposed to two 256MB sticks?
If so, no, that's not at all odd. Apple ships MacBooks with matched pairs because of the integrated graphics (it benefits from the speed of matched pairs since it shares main memory), but the Pro doesn't really matter so it is available with either single or matched pair configurations. I, for example, specifically selected to get mine with a single 1GB stick so I could fill the other slot with a 1GB stick from a third party to max it out.
Even if they DIDN'T sell it that way, though, you sometimes get oddball configurations with refurbs--they are previously owned machines after all.