30 seconds is not enough time for danger situation. But if you feel fear, open all door and window. There is no big issue. It could be handle yourself....

Light a match and walk around if the flame doesn't get bigger then your fine

No, open the windows but 30 seconds isn't very long at all. Make sure you can't smell gas anywhere before closing windows.

it was about a few minutes ago and I'm very worried?

I know it wasn't for a long time but I'm still concerned. We opened the windows and turned the fan off and stuff. Are we all good now?