Women:Are you okay with husband having a work best friend that is a female?

My husband (28M) has a pretty flexible job where he can talk on the phone all day if he wanted to. He talks to one woman for 3+ hours a day. When I am able to call him he never wants to stay on the phone long because he is “busy”. When I bring this up to him, he says that they are just “buddies” and I never let him have any friends. Would anyone else be bothered by this or am I overreacting?