Even talking to a radar unit, if you are requesting a Basic Service, the ATCO is not obliged to positively identify you on radar.
Based on DF traces (if available) and/or your intended routeing, it's a legitimate question.
Never assume that if you are in two-way with a radar unit you have been positively identified unless you have been asked to "squawk ident", do at least a thirty degree turn "for identification", or been handed over from your previous frequency.
To the OP, it may just be that the ATCO was anticipating a potential conflict with an a/c under a radar service, and just wanted to confirm who you were, and what your intentions were. Nothing more.