advice! interviewing associate told me to call him back

I had a first round interview last week for FT analyst in ER with a top MM. My interviewer was a Sr Associate. We went through the first 10 minutes with some basic fit questions. Then he asked me to give me him a stock pitch which I nailed because afterwards he told me that was one of the best pitches he's ever heard in an interview setting. He then asked me to give him my views on the economy. I did well on this as well. I guess my stellar performance up to this point kinda screwed me because after the pitch, he grilled with me a slew of extremely tough accounting questions which I struggled to answer. He told me that while he thinks I'm very knowledgeable and sharp, my lack of accounting skills was a deal breaker. However, he said he doesn't want to discourage me from pursuing a career in ER and with his firm. Since I'm taking the CFA level I this December, he said to call him back if I pass. I'm not going to put my all of my eggs in one basket so I'm going to continue to interview with other firms but this MM in particular is my top target. Has something similar to this happened to anyone? Should I take him up on his offer if and when I pass Level I? What should I do? Thanks.