whiff of gas when turning an appliance on or off is not unusual and not a major
concern. Odor of gas in valve box is not unusual but is
a concern, follow canary's advice, call gas company, they got all kinds of neat toys.
Not a bad idea to shut off gas when grill or pit not in use. Here's some toys that will save the knees, depending on what kind of handle is on your valve one of these may work or be modified to fit. There are other styles, the "pronged" ones have various spacings and often fit in notches around or holes in a round handle. They also make knee saving tools to open box.
Don't worry that box says "irrigation" basically a box is a box, may cause brief confusion for someone unfamiliar with set up, you can relabel with a paint pen. I suppose if you were to irrigate melons with gas, they'd float up for easy harvesting. Gas melons instead of water melons. Might get real exciting when roasting pumpkins.
Measure twice, cut once.
Look at the nail, not the hammer. Watch the fence, not the blade.
If you hook your thumb over your belt you won't hit it with the hammer or leave it layin on the saw table.