This, as strange as it is, is status-bydesign. The questions were unanswered when they got added to your feed, they are not anymore.
Each time you pull to refresh on the feed it looks for more things to add into yours and does so. However, it's possible for one of the questions we considered as "unanswered and this user might be interested in" to come back and get an answer later on in the day (or even sooner), making it so that "unanswered" label no longer applies. It still displays however, since it was unanswered when they label was made.
I don't really have a big problem with how this works right now, what I do have an issue with is the fact that the label doesn't change. This becomes a little bit more complicated when you have a series of unanswered questions returned, let's say 3, and the first one in the list gets an answer. Now the label applies to items 2 and 3, but not to item 1. I'll gladly take any suggestions for how we can change this on the presentation side.