IPhone :: IOS 5.1 Update Set Restrictions, How To Recover

I just updated my iPhone 3GS from iOS 4.3.5 to 5.1, and now Restrictions are set to "On". That was definitely not the case before I updated, and I do not know the 4-digit passcode to disable. Two questions: How do I turn off Restrictions without re-installing the OS? The upgrade to 5.1 took nearly 15 hours (a nearly full 32GB iPhone) and tied up the family iMac (late-2010 model 27" Core i7 quad-processor) for the entire time — I do not want to that again, especially if I cannot be guaranteed that Restrictions won't end up locked again.What happens if I keep trying different passcodes — is there a limit on the number of attempts? If so, what happens when that limit is reached? Additional info: not using iCloud; mail, contact, calendars still set to sync to MobileMe; everything else syncs via iTunes on the iMac.

Info:
iPhone 3GS, iOS 5.1