Puzzling - why is a Full GC triggered here?

[Kobe Bryant]

The following GC trace was obtained soon after the JVM was started
(a lot of transient objects are generated as a part of the start up and
hence
a lot of minor GCs).

( Xms = Xmx = 2G, NewGen = 1/3 of 2G, PermGen = 760m)

I see Full GC triggered (highlighted in bold below): the object space
occupancy
in tenured space is 2% - and yet a Full GC is triggered (I have elided
PermGen reports, as PermGen usage is about 2% and is healthy)

{Heap before GC invocations=2 (full 1):
 PSYoungGen      total 608256K, used 2016K [0x00000007d6c00000,
0x0000000800000000, 0x0000000800000000)
  eden space 540672K, 0% used
[0x00000007d6c00000,0x00000007d6c00000,0x00000007f7c00000)
  from space 67584K, 2% used
[0x00000007f7c00000,0x00000007f7df8030,0x00000007fbe00000)
  to   space 67584K, 0% used
[0x00000007fbe00000,0x00000007fbe00000,0x0000000800000000)
 PSOldGen        total 1421312K, used 0K [0x0000000780000000,
0x00000007d6c00000, 0x00000007d6c00000)
  object space 1421312K, 0% used
[0x0000000780000000,0x0000000780000000,0x00000007d6c00000)
 PSPermGen       total 524288K, used 10939K [0x0000000750400000,
0x0000000770400000, 0x0000000780000000)
  object space 524288K, 2% used
[0x0000000750400000,0x0000000750eaef28,0x0000000770400000)
*2012-03-26T22:35:49.121-0700: 0.614: [Full GC (System)AdaptiveSizeStart:
0.645 collection: 2*
AdaptiveSizeStop: collection: 2
 [PSYoungGen: 2016K->0K(608256K)] [PSOldGen: 0K->1809K(1421312K)]
2016K->1809K(2029568K) [PSPermGen: 10939K->10939K(524288K)], 0.0317230
secs] [Times: user=0.03 sys=0.00, real=0.03 secs]

Why was full GC triggered here? Is it because RMI DGC? Is there a way to
identify if DGC is triggering GCs?
PermGen is at a healthy and consistent level of 2%. I have hence elided
this detail above. And hence,
this cannot be the cause of full GCs.

thanking you
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