I am seeing the same, engine.
I emailed Bing about this 8 months ago and received a standard reply about .com domains appearing in Bing US unless the content-language meta tag is used in the head section of the page or the http header. This doesn't make any difference or the fact the site is hosted in the UK. I have page 1 rankings for search terms in Bing US but the same terms are on pages 3 or 4 in Bing UK.
Bing should allow site owners to choose their market as Google does in Webmaster Tools.