faint. If I've attended a university for one year but I didnot mention that on my resume, will I get into trouble?

How about GPA then? I got As for all the courses taken from the most recent school, and got a GPA 3.5 from the previous school. In the application form, I stated GPA 4.0 and 3.5 respectively. But the problem is, I transferred 3 courses from the previous school and for one of them I got B. If that B is counted into my final GPA, I'll not have a 4.0. Will this be detected in the background checking? Any trouble with it?

I hope I'm just 杞人忧天ing.