'Cracking' noise from rear diff.??
 

I did a search but could not find anything that matched the symptoms I've got.

Drove my car (2003 JDM STi) today for the first time since November. Has been in storage due to extreme weather. There was a bit of a thaw today so took the opportunity to go for a bit of a blast.
When pulling away from junctions there was a very noticeable 'crack, crack, crack' sound. Sounded like the rear diff. The roads were dry and free of ice where this occurred
I've heard this noise once before when pulling away quickly to the left at a junction. I assumed that it was normal noise as the LSD did it's stuff.
Today, however, it was much more frequent than before even under mild acceleration while pulling away from junctions. I could even provoke the same noise under heavy acceleration in moderate bends.
I took the car to a large empty car park and did some circles, clockwise and anti, and after several in each direction the noise disappeared and did not reappear for the remainder of the drive.
Is it possible that the long lay-up has caused some problem? Or does this sound pretty normal?
Any advice or comments would be appreciated.
Thanks.
Forgot to say that the car has covered only 5,000 miles.(8,000 kilometres)