Definetly, when ever a partner has tickled me its always been waaaaaay more ticklish, I've had good sessions with people I'm comfortable with but nothing compares to how comfortable I am with a partner and the comfort factor affetcs me greatly. I've also tried sessioning with people I'm totally uncomfortable with and have been completey not ticklish, one was with a very skilled tickler too, but nevertheless, nothing.
Its not the same for everyone I'm sure, in fact I wish it didn't matter so I could be just as ticklish all the time but that's just how I am.