Yep, that's what a new growth on a rossioglossum should look like, they're always very fat and succulent right from the start rather than thin and slender. You are right though, even though they're fat they should shoot up quickly once they start to grow. Your plant is probably in a bit of a shock after being moved from wherever it was growing to Houston (a tad warm for these plants) and also from being repotted, but I'm sure it will pick up again soon. If it were really unhappy it would have started to shed its leaves and the new growth would have gone mushy, so I wouldn't worry too much at this stage. Give it a bit more time to establish itself. Mine have just started to grow as well, so I'll try to remember to take some pics and post them here for you so you can compare them.