Yes. Of course, it's reasonable given that it reduces the number of connections (smashingmagazine.com/2010/03/css-sprites-useful-t…).
You can also make use of services like http://spritegen.website-performance.org/ to help you regenerate sprites in case you have made changes to your sprites or modified one of the images.
I would suggest you to go through the article on Smashing Magazine. You will get a better overview about why you should try to avoid using separate images.
As a side note, you can also try using svg.