I had my takedown since October of 2012 and I too have to strain... Although I hear it is not good on the pouch to strain... But it seems to just happen, like my body wants to bare down.

I strain but try to limit the pushing, if that makes sense... I know when to back off.

Same thing happens to me, Right when i sit down i end up straining a bit, once things start moving its like it found the door and the rest follows, after that once the "door" closes i have to strain a bit again to get the rest out, gas and all though thats usually harder to do. alot of times leaning to my left or your right i find helps as well, almost always to the point where one of the two cheeks is off the cushion.