Why is this?

[Brundo]

Here are links to two photos I shot several weeks back. I believe I was using Kodak Ektar 100 in an old Olympus OM-1. I'm wondering why shot one is sort of fogy while shot two is not. Help? I did not develop this roll myself I sent it off to a local lab.
1) September 29, 2015, 3:58 PM | brandonbrunswick | VSCO Grid®
2) September 29, 2015, 3:58 PM | brandonbrunswick | VSCO Grid®

 

[Ysarex]

The negative for the first photo is underexposed. If you compare the film side by side you should notice the negative for the first photo is much lighter than the second. The camera exposure for the first was not sufficient.

Joe

 

[Brundo]

Thanks. I thought for sure my exposure was spot on. Maybe it's time I take the olympus in for a tune up.