Odd Vector3 behavior (MOGRE 1.4.6)

Well i just experienced something that was REALLY strange to me:

Here some code that reproduces the problem (at least on my machine):

Vector3 vec;
* Console.WriteLine();

* indicates a breakpoint.
This does NOT always work the first time!

Just watch vec with the debugger when the breakpoint is reached.
THERE IS A OBJECT ASSIGNED TO vec?!?
How can this be?

Totally confused by the discovery i declared various variables of other mogre types but as expected they have the value "null".

Can someone explain this?

Could at least somebody verify this?

€: Vector3 is a struct not a class. This explains what happened.