The EGR valve can stick, the chances are if its starting to stick, sooner rather than later it will stick again.
The good part is, they are cheap to buy and so easy to replace.
http://cgi.ebay.co.uk/Vauxhall-EGR-Valv ... dZViewItem
You can also remove the EGR valve, buy a blanking plate from Vaux for £3 and get a small circuit from Vocky on here for £10. The car does not need the EGR valve, it is only there to allow less harmful emissions into the world!