"Updates" for app never purchased!

- In the MAS on my machine (10.6.7) I have a red badge showing on the MAS icon in the dock.

- I click and open the MAS, and it tells me I have "Updates".

- However, the update is for the "Twitter" app from Twitter, Inc (v.2.1), which I have never used/owned/downloaded EVER.

So how can i possibly have an update for it?!

(NB I tried signing-out, and then back in, but still shows the phantom update!)

Bug?

[I also notice that most of the apps I had before the MAS was released, that originally showed as "Installed" in the MAS soon after originally downloading it, are now showing as the price; even though they are the exact same point versions I already have ...bug 2?]