RFE on initial H1B application premium processing on 04/18/2017

I am a medical graduate. I will be joining residency program on H1B.

my case received RFE; the question asked is regarding to position, not about qualifications/eligibility.

what does that mean? how common is it to get a RFE like this?

is that a red flag? what r the chances abt rejection/denied H1B?