Popping noise from exhaust on start up

[BigCountry95]

I'm sure my truck is okay but i just want to make sure. When I cranked up after work today it made a single pop from the exhaust. Why?

 

[whippersnapper02]

I think it's a small backfire. Normal for the 4 bangers.

 

[BigCountry95]

Ight. That's what I figured but better safe than sorry. It made my heart skip a beat when I heard it. I figured my ol girl might I been sick. Thanks a lot man.