I have seen this issue listed on the other forums. It seems to be a common problem with the newest version of the OS. One thing you can do if you are not rooted, is to download Widget Locker. It provides the ability to manipulate your lockscreen in numerous ways.
If your rooted, on the other hand, you can download different fonts, or change the clock around basically however you want. Most of that is dictated by the individual rom you have on there.
Short of the above two methods, your options are somewhat limited, as the lock screen is in the root files.