I thought it unlikely, especially in view of subsequent infrared coverage which would probably have picked this up as a heat source.
Still, the 'mouth' of the african-mask-shaped outcrop does look like a dormant, deposit-encrusted fumarole vent (it has a raised rim all the way round), and the 'eyes' of the mask-shape correspond almost to the centre of the crater (arrowed) and does appear to cast a shadow towards its South-East edge - the dust deposits on top of other areas of white rock outcrop in this image seem to be very thin and don't cast shadows.

If the crater was volcanic rather than an impact structure, activity on a very small scale but over a long period ( I'm thinking mid-atlantic black smokers ) might account for the large amount of very dark dust inside Pollack.