Undercover cop followed my boyfriend home from food lion on western blvd to ID him for buying alcohol???

My roommate and I moved homes today in Raleigh and to celebrate my boyfriend (who’s of legal drinking age) picked up alcohol from food lion down the road from our new house. he got 3 bottles of wine and a 6-pack of beer (for 4 people).

It was around 8:30pm when he left the store so it was already dark but he passed the car on the way out and said he knew immediately that it was a cop. Then the guy followed him all the way to our house (my boyfriend knew this was happening and was sketched out so he made lots of random turns and even pulled into someone else’s driveway but continued to be followed all the way home). When he got out of the car to come inside, the cop got out of his car unmasked, in an unmarked car and wearing a sweater, said he was a police officer and asked to see his ID because he saw that he had bought alcohol from the grocery store. My boyfriend said “uh yeah, can I go get a mask first?” and at THAT point the cop goes “oh yeah let me get mine too.” The ID checks out (obviously, he had to show it at the store to even make the purchase) so he lets him go.

is this.... legal??? he’s white so it wasn’t a racial profiling situation but like, what the f*ck. It’s been four hours and he’s still pretty shaken up about it. Not a good vibe for this new part of town on our first night here 😕 (edit: fixed typo)