A friend of mine gave me this image:

http://i.imgur.com/loA7HCF.png

As you can see, the bottom chart shows the usual phases seen in any asset bubble. The upper chart shows the price of Bitcoins over the past few days with bubble phases used to describe them

To anyone with any financial experience, this whole situation does look like typical bubble behavior, especially given that the USD price of Bitcoins seems to have stabilized between $90 to $100, ie "the return to mean".

So if you're anyone in the mainstream media or who works in business and finance, your natural inclination is to call it a bubble. It's just force of habit.