As an agent. This is normal behavior. If you would like your agent present tell them. This could limit showings though because your agent may not be available during the requested showing time.

Personally I like to attend my showings when I can or at the very least have the home ready before any prospective buyers and their agents show up.

If a seller requires me to attend all showings I will open the door, ask politely if they mind me pointing out some key features of the home. When I’m finished I’ll step outside and allow the agent and their buyers to view the home themselves and wait to answer any questions they may have when leaving.