No, this kind of thing has been happening since long before Penguin. It especially happens with relatively new websites or those with a pile of recent changes.
Google would prefer to show either the real titles or their own construction taken from the page or backlinks. So just make sure your site has no technical errors - especially that robots.txt and/or meta tags are not accidentally blocking googlebot. Then keep working on improving your site and its marketing.
An easy check for crawling problems (which, as Ted says, can result in the URL-only listings you're seeing) would be to verify the site in Webmaster Tools and check the crawl reports. That's the highest priority to check, and if it comes up OK then there are other areas you would need to start exploring.