Well, when in your first year you can kind of tell who is going to be there another year.  When I worked in PA I could always tell for some reason (gut feeling) when someone was going to be asked to pursue other opportunities.  I actually had a first year that was all excited about his first job out of school.  Needless to say I actually enjoyed working with him a lot, I taught him a fair amount but he was on my engagements roughly 1/4 of the time but from the actual time that he was he always praised me on how I manage the client relationship so well and that I give him the guidance needed, etc.  But, for some reason I could just tell that they were going to cut him as I realized that he required additional time from a senior's position.  He was actually going to purchase a new car during busy season and I told him to just wait it out and that when I first started I bought me a new BMW but wished I just kept my old car given how you just wear the car down during auditing for the amount of travel you do, so he pushed off the purchase and two months later he was let go.  He had personality conflicts with most of the other seniors and managers but with me he got along and of course I would hear what others always talked about.  So I wouldnt' just classify one mistake as being a mark on your record its just after being in PA for a little while you can just tell who they want to stick around, who they abuse (people with H1's) and people who they want out. 

Once again, I always say that majority of people 99% leave PA, so get the best name on your resume for the first 5 years and leave for a better paying job with less hours.  View PA as an extension of Grad School, pay your dues for a couple years and leave <quote from a CFO on one of my first engagements> :)