Http check causing httpd.exe process to suck up memory

I am running apache for windows version 2.2.10 with php 5.2.6 and perl 5.8.8.
My nagios server is on a Ubuntu 7.10 server and is quite stable, however i notice that the httpd.exe process on the windows box takes approx 160meg when starting and in about 2 days is upto 760meg in size. the only thing in the access logs that is accessing it is the nagios plugin check and a googlebot.

Does anybody have any suggestion as to why it seems apache is not releasing the memory after the nagios query?

eg:
99.240.31.234 - - [03/Dec/2008:11:52:50 -0500] “GET / HTTP/1.0” 200 2960 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:12:01:00 -0500] “GET / HTTP/1.0” 200 3667 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:12:02:50 -0500] “GET / HTTP/1.0” 200 2960 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:12:11:00 -0500] “GET / HTTP/1.0” 200 3667 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:12:12:50 -0500] “GET / HTTP/1.0” 200 2960 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:12:21:00 -0500] “GET / HTTP/1.0” 200 3667 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:12:22:50 -0500] “GET / HTTP/1.0” 200 2960 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:12:31:00 -0500] “GET / HTTP/1.0” 200 3667 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:12:32:50 -0500] “GET / HTTP/1.0” 200 2960 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:12:41:00 -0500] “GET / HTTP/1.0” 200 3667 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
65.55.208.190 - - [03/Dec/2008:12:41:15 -0500] “GET /catalog/index.php?cPath=1_17&sort=2a&language=es HTTP/1.1” 200 21590 “-” "msnbot/1.1 (+http://search.msn.com/msnbot.htm)"
99.240.31.234 - - [03/Dec/2008:12:42:50 -0500] “GET / HTTP/1.0” 200 2960 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:12:51:00 -0500] “GET / HTTP/1.0” 200 3667 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:12:52:50 -0500] “GET / HTTP/1.0” 200 2960 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:13:01:00 -0500] “GET / HTTP/1.0” 200 3667 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:13:02:50 -0500] “GET / HTTP/1.0” 200 2960 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:13:11:00 -0500] “GET / HTTP/1.0” 200 3667 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:13:12:50 -0500] “GET / HTTP/1.0” 200 2960 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
66.249.71.197 - - [03/Dec/2008:13:13:23 -0500] “GET /robots.txt HTTP/1.1” 404 300 “-” "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)"
66.249.71.197 - - [03/Dec/2008:13:13:24 -0500] “GET /catalog/index.php?cPath=2_20 HTTP/1.1” 200 21930 “-” "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)"
99.240.31.234 - - [03/Dec/2008:13:21:00 -0500] “GET / HTTP/1.0” 200 3667 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:13:22:50 -0500] “GET / HTTP/1.0” 200 2960 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:13:31:00 -0500] “GET / HTTP/1.0” 200 3667 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:13:32:50 -0500] “GET / HTTP/1.0” 200 2960 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:13:41:00 -0500] “GET / HTTP/1.0” 200 3667 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:13:42:50 -0500] “GET / HTTP/1.0” 200 2960 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:13:51:00 -0500] “GET / HTTP/1.0” 200 3667 “-” "check_http/v1991 (nagios-plugins 1.4.12)"
99.240.31.234 - - [03/Dec/2008:13:52:50 -0500] “GET / HTTP/1.0” 200 2960 “-” “check_http/v1991 (nagios-plugins 1.4.12)”