I've been grinding quite fine with this stuff as I over-roasted it rather (no 2nd crack it seems). When I pull a shot I get quite quick flow for about 10 seconds (after 5 seconds pressure building before flow) and then it stops
. When I release the prtafilter it is very soggy on top. It seems that after a while the puck becomes more resistant to the water and the flow stops, how wierd is that? 
I can only think that there is some strange effect with decaf beans that the grounnds swell more, and restrict the flow after a while.
