SMS as pop-up alert?

[Shervrar]

So a friend just sent me a text (SMS), and instead of appearing in the thread of our conversation on the messaging hub, I got some sort of alert on my screen. Does anyone know what this is?
I attached a screenshot so you know what I mean.
The message was sent from an iPhone. As you can see I got a smiley face "", but the actual message sent was "!! ".
PS: I edited the name of my friend on the screenshot...