I've a D2a TD5 too and it does the same thing (rush of air from SLS) about 30 seconds after switching off with a slight lean to the left. I was worried but found a web page (can't find the link now I'm looking for it - some about 'definitive D2 suspension page') that described it as perfectly normal. It pumps straight back up on restart and hasn't given any dramas. I'll have a look for the site and post the link if/when I find it.
cheers,
bidds

