Slow Tire Leak

2000 Accord--found a near flat tire last night. Pumped it up and found that the pressure dropped about 5 psi over night. Took the tire off, first thing
I checked was the stem with a bit of water---.lucky me-- It showed a small leak. Tightened the stem and the leak stopped. Didn't want to trust it so I just replaced the stem. Just curious, what the heck would cause the stem to loosen up a bit? I've seen worn seats but never this type of problem. MLD

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file
Upload is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.