When in doubt, throw it out. 10 years definate toss and replace, don't even think about that one. Even the home sizes, you should also turn them upside down and back a few time a year to prevent the ABC dry chemical from clumping up.
And remember, change your clock, change your smoke detector batteries. Those also have date created and date to toss. If you don't see one for the battery style detector, consider replacing those as well. All else fails, call Headbanger.