Thanks for all the replies everyone!
I've keg hopped before but never with pellets and the one time I got significant carryover of hop pellet material into the keg I spent a very frustrating evening releasing the pressure, pulling the out post, cleaning it, putting it back together, pouring half a pint, having it clog again...
repeat until finally I had my housemate with the smallest arms reach into the keg and rubber band a bit of tea ball and muslin over the end of the out tube.
Steve, you probably tasted some of that batch, it was the 'session' IPA I brought to GBA XMAS party two years ago. This one is Also for that party this year so flashbacks...
thanks again!