My mom's 23lb ragdoll cat bites her when she leaves ..is this normal ?

Since I am getting all my pet questions out tonight lol.. My mom has a 2 yr old Ragdoll cat 23lbs--yes she is way overweight and I have told my mom this even for a ragdoll she is a SEACOW..she has rolls on her rolls...anyways ..she does some of the craziest things - my main concern is -- whenever my mother goes to leave she will follow my mom and bite or attempt to bite her foot or leg before she leaves --not enough to draw blood but she can leave a mark at times..she then screams and cries by the door for at least 15 mins after my mom leaves.it is CRAZY!! She only does this to my mother and another example of her antics ...my mother will be watching tv and Prissy will jump up and bite her on the toe or foot for absolutely no reason --and my mom's foot will be totally still --she does a lot of really smart and cute stuff as well --but I swear she is bipolar and to reinforce that belief --she is a tortie point and one side of her face is blue and the other is cream -- i like to call her Dr. Jekyll/Mr Hyde lol.....one minute you can be petting her and she is purring and then next if you ruffle her fur the wrong way while petting her she will grab your hand with her teeth or take of and hiss .. she is psycho -but it makes her interesting I guess..lol I know she is purebred she has papers from Trex dolls ragdoll in SC -they specialize in really LARGE ragdolls but she has exceeded I do believe anyways i don't think for a minute she lacks the fight or flight skill some say ragdolls lack lol.. anyways ok I'm done --just thought I would share her crazy behaviors so I can confirm with my mother her cat IS abnormal lol