Does WP “cache” templates?

This is weird. Everything was going fine, but I tried adding a query_posts statement to one of my template files so the page would display only posts from a certain category. It didn’t work. After more trial & error, I discovered that suddenly nothing I did to the template file was having any effect! I could change the name of the sidebar include, even delete all the code in the template and the page still loaded exactly the same. I cleared my cache, logged out, restarted my browser, nothing.

I double (triple-, quadruple-) checked: the template file
is the one associated with the page. (I even un-linked it and re-linked it.) I tried changing the name of the template and linked to that. I could even delete it from the directory and the page still loads. I created a new page and linked to the same template file, and it was fine: changes I made in the template were reflected in the page. But not with my original page.

Any ideas? Is it possible the database got messed up and it’s using an older version of the template file I can’t access any more?