What does the 'deer in headlights' look mean?

[JuliaLoves55]

I saw my crush in the hallway (we'd seen each other there before) and he just stared at me with this scared deer in headlights look. Please explain?

p. s. we're not really friends so I wasn't expecting a hello but before when I'd seen him we either simply made brief eye contact or just passed by each other without anything

[CarpetDenim]

Deer, when caught in the headlights of a car, tend to become temporarily frozen or paralyzed in fear, and often are not able to move or even conjure a thought. When someone is described as looking like "a deer caught in headlights," it indicates whatever they're looking at surprised, shocked, or scared them to the point of paralysis.
upload.wikimedia.org/.../...ng_into_headlights.jpg
careerconfidential.com/.../...ockphoto13347250.jpg

[JuliaLoves55]

so I scared him?

[CarpetDenim]

Or really surprised him, not necessarily fear.

[JuliaLoves55]

oh ok got it, thanks!