I found this info, as a comment from Aaron . Is this attached to a KB or anything I can take back to my boss ? Sounds like an 'External' monitor is my only hope ....
As described in CR97857, the monitoring daemon, bigd, appends one or more extraneous CRLF's to the TCP, HTTP and HTTPS monitor send string. As RFC2616 states there should be no CRLF following the POST body, using an HTTP or HTTPS monitor with a POST request will result in a request which the server *may not* see as valid. In that case, you'd need to use an external monitor.
If this is something you'd like to see fixed, you can contact F5 support and request your case be attached to the CR.
http://devcentral.f5.com/Tutorials/TechTips/tabid/63/articleType/ArticleView/articleId/169/LTM-HTTP-Monitoring-with-POST-Request.aspx