It's common for interviewers to mention travel requirements for a job and ask if it will be an issue. This is likely because the job may involve frequent trips to different locations or meetings with clients in other cities or countries. The interviewer wants to gauge your willingness and ability to travel before making a hiring decision. If you have concerns about travel, it's best to talk with the interviewer to see if any accommodations can be made. If traveling is not an issue, let the interviewer know you are excited about that aspect of the job and how you have your passport ready!