I hold a 10 yr multiple entry B1/B2 visa. I entered USA last month on B2 visa to do a elective rotation in medicine at cornell university for 4 weeks. My acceptance letter mentions that I have to enter on tourist visa to do that rotation and i showed the same letter at POE. However immigration officer asked me what if you get accepted at cornell. I explained him that its not like that i ll be accepted and im gonna finish rotation and go back home where im a medical student..He checked my ID card and gave me 6 months stay......But he crossed "PROSPECTIVE STUDENT" box on my I-94. Now im back .....and I will be visiting US again next year....Please let me know that whether that "PROSPECTIVE STUDENT" could trouble my entry in future......like is it possible that Im asked questions like......Why u didnt change to F1 status????