I would be very, very surprised if this was anything to do with the original leak; if it had been leaking for 4 years your joists will be rotten and chances are you'd have gone through the floor long before now. As it's near the toilet I'd say that's what's probably causing the problem now, if you can, lift the floor around it and check it's not leaking. If there is another leak you can claim for escape of water (usually covered on standard policies) but it will be a new claim, with an excess (if applicable) and your premiums will probably go up. If I were you I'd try to investigate the cause and extent first, and then consider claiming. If you have trace and access on your policy and you do decide to claim then your insurers will cover any damage done while you tried to locate the leak, otherwise you'd have to cover it yourself.