Bathing with 6 year old

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My daughter takes showers and baths mostly alone. I help her wash her hair or I’ll scrub her if she is extra dirty. I did bath with her when she was younger. HOWEVER - NOW when I take a bath, she’ll come in the bathroom and beg to come in with me. I usually let her. It happens once or twice a month. We just soak and talk or she’ll bring a couple Barbie’s and we will play. I think she likes the alone time without her baby brother. Is this strange behavior? Should I not allow it? My thoughts are that it might be more damaging to completely shut her off from occasionally soaking in the tub with me than it is to do it until she no longer wants to. Any advice?