Fragrance Out Of Nowhere In Home

This is not so scary experience but a mild one. But still the questions remains same, how did it happen?

FYI, I don't use perfume neither my wife uses it when in home.

This incident happened while I was staying in Singapore along with my wife and my 3 year old kid. I got a job there and we had rented a very nice 3bhk HDB (housing development board) unit. In this unit, one of the bed rooms was locked as it had owner's stuffs. So we had no access to it. We were using master bedroom for ourselves and another bedroom was used to keep our belongings.

One evening, I was watching Netflix in the living room. On one wall there was TV and the wall perpendicular to it had 4 windows. I generally keep the windows open to enjoy the minimal breeze we get in Singapore. All of sudden I smelt fragrance same as women's perfume out of nowhere. The fragrance was mild first and then strong and then faded away as if a lady wearing sweet perfume passed by me. I can only think of a lady due to the type of smell it was. This whole experience lasted for 10 seconds maybe. To reconfirm if I was hallucinating or it's real, I asked my wife if she smelt perfume too? She was doing household work in living room. She said she did smell it too. We simply ignored that experience and resume what we were doing. There was no bad energy or aura and rest of the day went well.

After a few days same incident happened again in the living room only. This time as soon as I smelt it I immediately asked her are you smelling the perfume right now? She said yes. And as before the fragrance vanished in few seconds. Nothing else happened that day too. The previous tenant was my friend and I had asked her when she visited us about the smell and she said "don't prank me or try to scare me, I am sure you are making it up". I said "I am serious" and she didn't respond and changed the topic. Seems like it happened to me and my wife only.

We can't enquire the broker or tenant as it didn't trouble or was not a concern at all. Just out of curiosity want to know what could have happened those 2 events? I have tried to Google it but didn't get any firm explanation.