Create pdf from local webpage

I have encountered the following behaviour - is it a bug? I am developing the home page for a website and want to send a pdf of the page to a collaborator as well as retain the pdf in DTPO. So I display in Safari the index.htm file (which is stored locally) and save a pdf of it to DTPO using the Safari bookmarklet. A file of type PDF+Text is duly created in DTPO. However, if I now drag this pdf file out of DTPO onto the desktop, it creates an index.htm file on the desktop! This behaviour seems to be specific to local files displayed in Safari - if I display a webpage from the internet, save a pdf using the bookmarklet and drag it to the desktop then it creates a pdf on the desktop.
I am using DTPO 2.0.9 and Safari 5.0.4
PS I realise there are other ways of getting a pdf to my collaborator - the point of this post is the odd behaviour.

Trying this over here, opening a local index.html document. Used the PDF bookmarklet (the Safari plugin does not work on file:/// URLs). The file in DTPO is PDF+Text and has the name of the web page (My Test Page). Dragging this to the desktop, the file is still a PDF, but is named index.pdf. If I export the file (File > Export > Files and Folders) I also get a PDF, but now it is named My Test Page.pdf. Check your dragged file - maybe it is really a PDF?

Many thanks, Korm, for taking the trouble to look at this. I opened the dragged-out file in TextWrangler and it is definitely htm. However, having closed down DTPO and the programs creating the website, and re-started the system, I can no longer recreate the effect. Dragged-out pdfs from file:/// URLs now stay as pdfs. Gremlins…… Thanks again.