Take a closer look around the plant, and see if there are any more like it. If it's a hermie, more nanners will usually follow, directly behind the original, making them look like a bunch of grapes. Is this only one plant that's like this?

Sometimes the pistols get stuck inside the calyx, and can start swelling up and looking like nanners. My Shishkaberry get's those 'pistol zits' every once in a while. Used to freak me out, and I really don't want to know how many perfectly fine ladies I culled as a result of my 'hermie panic'. (a few years back) I'd wait a few days to see what it is going to do.

Or, pluck it off and act as if it wasn't there in the first place, lol.