Tesco interview questions

Filled in an application from online. Got a phone call a couple of days later asking me to go in for an interview in the store. Was then interviewed by manager and assistant manager. Felt more like a terror investigation than an interview. Questions were nothing like I had expected and quite difficult to answer even though I had appropriate experience. Would of thought I was going for a manager position, not checkout assistant. Both interviewers were friendly but did not make me feel comfortable and relaxed when answering questions.