Am I overreacting?/How do I ask if my dad is suicidal?

Uh yeah… so it’s as the title says, potential triggers for suicide. There was a maintenance guy over, and he walked into the room and my dad followed behind him. My dad made eye contact with me and mimicked shooting himself in the head. He’s never done something like that before. He does take medication for depression. I’m terrified he’s gonna do something. He’s probably just annoyed at the maintenance but it was so out of the blue. He seems okay, but I know that means nothing when it comes to suicide. I know I should probably just talk to him, but I’m also scared he’ll get annoyed or defensive if I ask. What if I make it worse by asking? How do I even broach the topic? I’m scared to ask my mom about it cause I don’t want her to worry or to bring it up to my dad that I told her. I love both my parents with my whole being but I’m terrified. I do not have good experiences with people mimicking shooting themselves in the head. I have no idea what to do! Am I overreacting? I feel awful and so incredibly ill over this… I’m probably just making this a big deal but… Sorry and thanks for taking the time reading this…