Yes, Patagonia jackets do run small and tight especially the slim fit. That's why it is recommended to size up the jacket from small to medium or large.

Do Patagonia sizes run large or small?

Keep in mind Patagonia calls this pull over a slim fit. These run small! Size up one full size from your normal size. She is always a small to even extra small in tops or jackets.

Does Patagonia fleece shrink?

Do Patagonia fleeces shrink? The answer is No. You can't shrink the Patagonia fleeces because they are used along with polyester, which is not like any fabric and thus takes a very high temperature to relax its structure and shrink.