Yes, to the East, too
Yep, that's the rim. You can also see a bit of it faintly in some of the recent pics looking to the east, with the rim very fuzzy behind the Columbia Hills.
JPL agrees, as there are some "press images" showing that rim segment towards Ma'adim (the one you copy above) in which the caption explains that we are seeing the Gusev rim and the notch in it cut by Ma'adim. The captions note that the dust has been settling out of the atmosphere and so visibility has been improving.