Female in Heat

I'm just curious, but does anyone else have a female that gets kind of mean when she's in heat? My girl Roxy normally is very affectionate and nice to her brother Viper, however when she goes into heat she gets a little more aggressive with her affection I guess. She doesn't bite and draw blood or anything serious, but she does groom the male's fur a lot more causing a few fur slips causing him to bark at her, get mad, and run away from her. She also spends a lot of time following him around while making noises and barking at him. It doesn't seem like fighting, but perhaps she's trying to force him to mate with her?

They've been doing this for 6 years whenever she goes into heat, so I'm not concerned that she is hurting him. Mostly I'm just curious if this is normal behavior.