Correct. We can use the prefix 'mid-' in many different situations: It's coldest in mid-winter. She interrupted me mid-sentence. I was mid-thought when the phone rang. Be aware, though, that it's usually considered slang, so be careful when you use it. We don't use it for every situation, but I think it is becoming more common as a replacement for "in the middle of X". "Mid-X" is shorter and easier to say and write.