sol 90-91 animation:

This view seems to be the "look at every sol" target. The 90-91 changes again include a slight change in the location of the tip of the solar cell panel which I noted in an earlier animation.
Since it seems to be repetitive, my guess is it is either a wind driven "flutter" - or perhaps a temperature driven "flexing". I'm sure the Phoenix guys know which.
Er, again, lots of very suggestive shapes to an old fossil collector. ( the old collector - not old fossils: well, actually both. )