I just had something really creepy happen to me. Like right now

I was upstairs just sat bored because my parents are out tonight. And my brother comes home with food and my dog doesn’t bark because she recognises the sound of the key as someone who actually lives here. (She normally barks like crazy if someone posting something or knocking that we don’t know) so she’s basically my alarm system.

I saw him enter as I’m coming down the stairs to get a drink. I lock the door after him because he always forgets. And I’m 100 percent sure I did. And then about 10 minutes later after sharing food with my brother I see I missed a call with my cousin. I call him. I call him for exactly- wait let me check. 20 minutes. Halfway through the phone call. I hear my dog gate open, but no barking from the dog. Which is strange, but I thought my brother was leaving to play soccer or something. And I hear it close after it opens. No barking still. Then the door closes.

I run down 5 minutes after the phone call and check. I see him in his bedroom so he must’ve just grabbed a water by the front or something? The doors unlocked though. But I just saw my brother in his room on the way down… and I definitely locked that door. He said he heard someone come in too and thought I WAS going out. I checked every crevice of the house so far. I’m above the front door so I keep looking out the window to see if anyone’s out there.

But the creepiest part is that my dog didn’t bark?? She’s basically an alarm for anyone we hardly know entering the house. I’ll bring my friends over or a plumber and she’ll go mad. But no barking?? And I definetly locked that door. She’s bit me before because someone else was at the door? I had a weird dream last year that reminds me of this situation too, about the general area of the house I’m in. I don’t believe in ghosts but this is just really strange. Who would the dog know that has a key?? She barks when I come in for gods sake! I’m freaked out.