Maybe G updated PR. Some sites (about 8) which I'm exchanging, changed & increased, but mines is not So and yours? Check it and post here Thank
I cheched "digpagerank" and almost all of them are showing "OFF" - so that's a good sign, right? http://digpagerank.com/index.php?url=www.YOURDOMAIN.com&dc=18
The digpagerank tool seems to be down, as usual. Check out http://www.seocentro.com/tools/search-engines/pagerank-dc.html
No difference on mine either. Could be any one of hundreds of other factors, look at things like domain/site age, speed it loads, relevancy to inbound and outbound links, etc