DHL Global Forwarding, Freight Import/Export Specialist interview questions

Applied online, next day DHL HR called and arranged an interview for the following week. Interview went great, manager was easy going and so lovely. Got offered the position. Did a medical exam. HR needed references, was advised to supply anyone at current employment as there were issues with with previous workplace referee not picking up. HR started asking the current workplace colleague referee some weird questions, eg, do you like it here. Asking my colleague about their experiences.. not sure why as they were meant to talk about me. HR then advised not to tell my current workplace where I am going even though they spoke to someone at my workplace already.. it was a bit weird as if she was hiding something. In the end decided to stay at current workplace.