Clenching teeth and fists

Hi moms, The last few months when my 13 month old gets frustrated, especially when I would tell her no, she would clench her fists and teeth and start shaking. At first I found it funny and sometimes as a joke I would ask her to do it because i thought it was cute. Tonight the clench fists and teeth looked a little different. I thought she was having a seizure. It happened when I was changing her on her changing pad in her bedroom, but I woke her up to change her because she pooped and she stretched her arms above her head and stiffened up and clenched her teeth. I picked her up after the diaper change and she did the same- clenched teeth and arms out shaking. Is this something I should be concerned about? I know she’s done it before but this time it just looked different because she stared straight ahead and did it and then it happened a few more times after that. Should I be concerned? Is this something your toddler does when maybe they’re cold or upset?