Calling an elderly person old offensive?

Is calling an old man old or lady offensive??? What are your opinions I just went to a job interview at a nursing home and used the word old and was bitched out by the boss lady there I didn’t mean to say it in a bad way I just said “old man” 😒 she hurt my feelings after I left there. She was pissed I used that term she said it was disrespectful, all I told her was I had worked with that “old man Fred and he was sweet” and she literally gave me a huge speech and was rude to me about it. caught me sooo off guard.