I got the same impression - like the edge of the cloud was a little bit
brighter, but I attributed it to contrast with the really bright central
part. Now, when you see it too, I start to think that maybe it is real.
In any case, today my impression is of more even brightness and more
distinctive (sharply cut) edge than yesterday. Yesterday it was way
more fuzzier.
A picture should be able to resolve the ring issue conclusively... If
there is a ring, however, we should not expect the comet to get much
brighter than what it is now, right? (My thinking is, a ring would mean
that it stopped or at least it reduced outgassing since the initial
"shell" was blown off. But I'm not a comet expert...)