My dog makes a noise when she is nervous or curious? Should I be concerned?

For as long as I can remember my 6 year old chihuahua has been making a noise that similar to a snort when she is nervous or curious. it's not a reverse sneeze. I have a 2 year old chihuahua that I got as a puppy and he picked it up from her. They don't snore or have any breathing problems. I have 2 other chis that were adults when she started doing it and they don't do it. Maybe I should be worried. I'm not sure how she is able to make that noise.

I was taking a video of the 2 year old and when he noticed something in my hand he made the noise while he checked it out and then stopped. it's a good example https://youtu.be/jfQOgKw8XsE