Comments seem to be formatted against original text in the new top bar inbox:
The original text of that comment read,
That was edited 5 seconds later to prepend the "+1" and lower-case the "A".
Although I kinda like the idea of a filter that would remove "[+-]\d" from the front of comments, nothing like this exists in the system right now. And if it did, it'd act on the actual comments, not just the inbox.