[racket] racket http server, major GC: -216 bytes collected

Hi,

today I was dabbling around with my servlet study, and switched
on debugging output for racket. 

  stefan at g128 racket % racket -W debug -u vacation-loop.rkt
  GC [minor] at 1484840 bytes; 644984 collected in 1 msec
  GC [minor] at 2219568 bytes; 650160 collected in 1 msec
  GC [minor] at 4256376 bytes; 1282232 collected in 4 msec
  GC [minor] at 5544024 bytes; 1268200 collected in 4 msec
  GC [minor] at 8433888 bytes; 2004064 collected in 7 msec
  GC [minor] at 11301992 bytes; 2566680 collected in 9 msec
  GC [minor] at 14976456 bytes; 3075320 collected in 12 msec
  GC [minor] at 19656896 bytes; 3690896 collected in 12 msec
  GC [minor] at 26845544 bytes; 4950472 collected in 26 msec
  GC [minor] at 33867744 bytes; 6128456 collected in 21 msec
  GC [minor] at 42413848 bytes; 7560344 collected in 26 msec
  GC [minor] at 54035040 bytes; 8792384 collected in 40 msec
  GC [major] at 69836240 bytes; 15243240 collected in 112 msec
  GC [minor] at 84420144 bytes; 18721472 collected in 56 msec
  GC [minor] at 99513800 bytes; 21027008 collected in 75 msec
  debug: I'm here
  GC [minor] at 113078792 bytes; 24509152 collected in 71 msec
  debug: now I'm there

At this point I went away for a few hours and this is what I found
when I came back:

  GC [major] at 89671472 bytes; 40452096 collected in 103 msec
  GC [major] at 49219376 bytes; 0 collected in 91 msec
  GC [major] at 49219376 bytes; 38520 collected in 88 msec
  GC [major] at 49180856 bytes; 0 collected in 88 msec
  GC [major] at 49180856 bytes; -2768 collected in 89 msec
  GC [major] at 49183624 bytes; 0 collected in 88 msec
  GC [major] at 49183624 bytes; -5768 collected in 87 msec
  GC [major] at 49189392 bytes; 0 collected in 89 msec
  GC [major] at 49189392 bytes; -1968 collected in 89 msec
  GC [major] at 49191360 bytes; 0 collected in 88 msec
  GC [major] at 49191360 bytes; -384 collected in 88 msec
  GC [major] at 49191744 bytes; 0 collected in 89 msec
  GC [major] at 49191744 bytes; -216 collected in 88 msec
  GC [major] at 49191960 bytes; 0 collected in 89 msec
  GC [major] at 49191960 bytes; -216 collected in 88 msec
  GC [major] at 49192176 bytes; 0 collected in 88 msec
  GC [major] at 49192176 bytes; -384 collected in 88 msec
  GC [major] at 49192560 bytes; 0 collected in 88 msec
  GC [major] at 49192560 bytes; -216 collected in 88 msec
  GC [major] at 49192776 bytes; 0 collected in 88 msec
  GC [major] at 49192776 bytes; -216 collected in 89 msec
  GC [major] at 49192992 bytes; 0 collected in 87 msec
  GC [major] at 49192992 bytes; -384 collected in 88 msec
  GC [major] at 49193376 bytes; 0 collected in 88 msec
  GC [major] at 49193376 bytes; -216 collected in 88 msec
  GC [major] at 49193592 bytes; 0 collected in 89 msec
  GC [major] at 49193592 bytes; -216 collected in 88 msec
  GC [major] at 49193808 bytes; 0 collected in 88 msec
  GC [major] at 49193808 bytes; -216 collected in 88 msec
  GC [major] at 49194024 bytes; 0 collected in 89 msec
  GC [major] at 49194024 bytes; -384 collected in 88 msec
  GC [major] at 49194408 bytes; 0 collected in 89 msec
  GC [major] at 49194408 bytes; -216 collected in 88 msec
  GC [major] at 49194624 bytes; 0 collected in 89 msec
  GC [major] at 49194624 bytes; -216 collected in 88 msec
  GC [major] at 49194840 bytes; 0 collected in 88 msec
  GC [major] at 49194840 bytes; -384 collected in 91 msec
  GC [major] at 49195224 bytes; 0 collected in 92 msec
  GC [major] at 49195224 bytes; -216 collected in 88 msec
  GC [major] at 49195440 bytes; 0 collected in 89 msec

During this time no requests should have been reaching this
server (running on localhost on a box behind a firewall).

I don't know at what points in time these major GCs occured,
but I am a bit worried about those negative numbers that are
"collected" while the server is sitting idle.

Does anybody have an idea where this is coming from? Or
how I could go about locating the source of this misbehavior?
Or is it just much ado about nothing?

Curious,
s.