why my spring session scoped bean is shared across sessions?

i have a simple pojo UserQuota with 1 field quota in it:

@Component
@Scope(value = "session", proxyMode = ScopedProxyMode.TARGET_CLASS)
public interface UserQuota {
    public int getQuota();
    public void setQuota(int quota);
}

now, i used two different browser windows (firefox and chrome) to log into my web application as two different users. to my surprise, when i set the value of quota (with setQuota) from one session, the new value becomes available to the other session (when getQuota is called). i was expecting each user session will have its own bean instance; isn't that what session scoped bean in spring is for?

i must be missing something. what could it be?

edit:

the implementation class looks like this:

@Component
public class UserQuotaImpl implements UserQuota {

    private int quota;

    /**
     * @return the quota
     */
    public int getQuota() {
        return quota;
    }

    /**
     * @param quota the quota to set
     */
    public void setQuota(int quota) {
        this.quota = quota;
    }

}

and finally here is how i use the session bean:

@Component
public class UserQuotaHandler {

    @Autowired
    private UserQuota userQuota;

    public void checkAndUpdateQuota() {
        int quota = userQuota.getQuota();

        // i use my business logic to decide whether the quota needs an update
        if(myBusinessLogic) {
            userQuota.setQuota(someNewValue);
        }
    }

}

i am using context:component-scan in my xml config file. it may be noted that most of my other autowired beans are singleton beans which seem to have been working as expected

You'll want to annotate your concrete bean class with the session @Scope, UserQuotaImpl in your case.

Spring ignores the @Scope on any superclasses or superinterfaces of your concrete class. Since your type doesn't have any explicit @Scope annotations

@Component
public class UserQuotaImpl implements UserQuota {

Spring assumes you meant to make it a singleton bean.