I'm no expert on phals, but the general rule I've been quoted says that, unless the medium is decomposing, or the plant has completely outgrown the pot (both of which would manifest themselves in dead roots and an overall unhealthy look), don't "shock" the plant by repotting it right away. Another piece of advice I've been given is that, especially if the plant is in active growth - and the new leaf and green root tips suggest that it is - if you WANT to repot it, this is a good time to do so. It's not spiking or budding, so repotting wouldn't interfere with that.
All of this said, this phal looks really good as it is. The roots will stay healthy, especially if you mist it regularly. It seems to me to be in the right size pot - you want the smallest that will comfortably fit the roots, and avoid "overpotting". Be careful not to leave water in the well formed at the leaf crown - that leads quickly to crown rot.
So... upshot? I'd leave it as is for now, and watch carefully to see if those roots start to extend significantly, or they start to turn white or brownish.
That's my instinct - other members may well disagree (in fact, the more members you poll, the more entirely different answers you'll get).
Loks like a really good little plant, with lots of potential - nice buy. Hope you have more luck with these things than I have had.