Search BAS_AS log for vendor.xml and see does it returnes error. Good way to check if your vendor file is up to date is to go to BlackBerry Solution topology > BlackBerry Domain > Component view > View (BlackBerry Enterprise Server) and see if the latest BB models are listed there e.g. 9900,9810,9850,9860 etc. Note that you may need to enable Enterprise Server Policy to see the list of models.
If they are listed there then you should be OK. There are other methods e.g. searching BBAS-AS log. BAS tries to check for a new xml files 10 minutes after an hour all day long e.g. 13:10,14:10 etc. http://www.blackberry.com/btsc/KB13589
Or check global settings table in SQL server. Hope this helps.