I've been rattled by every job interview I've had. That includes interviews for roles that I'd been courted for. It includes interviews for jobs I didn't even want, where I was interviewing mostly because a friend had asked me to. One of those interviews was for a company I actively disliked and would under no circumstance work for. I didn't sleep the night before! I did a multicast streaming media company in the late 90s and owned the router; later, I interviewed at a friend's company, got asked how to implement Towers of Hanoi without recursion, and for the rest of the day forgot everything I knew about routing protocols --- despite having spent the preceding two years doing nothing but implementing them.
Job interviews suck. They're hostile processes that involve complete strangers not just sitting in judgement of you, but also working under the delusion that their job is to break you so they can avoid hiring "B players".
I basically interview people for a living now and pay pretty close attention to this, and have come to the following conclusion: there is zero correlation between how people comport themselves in job interviews and their ability to do a job.
My best advice is, know the stuff you know. If you want to bone up on algorithms and data structures, don't cram. Implement them in your most comfortable language and watch them work, and go to the interview knowing not that you can recite them from memory, but that push-to-shove you can in fact throw down and get them working. Then just answer questions honestly.
The hardest interviews you take might be for the worst, most dysfunctional teams; a mean (or even just wicked) streak in interviewing candidates is a sign of broken teams, not weak candidates.
Good luck!