Why do some waters become temporarily obsessive?

Another quick overnighter to the Cheshire weedy water produced twitch,twitch,twitch from midnight for 1/2 an hour, I thought the rudd had found my bait.

After winding in thew rods I saw that the baits haden't been touched, so maybe the hook was covered in weed and the bait only was being picked up.
This can be a problem with casting out before sunset, as the weed then stars to fall down, masking the bait and hook.
A re-cast produced mirrors of
24.02 and
19.10 lbs.
Then a good night's sleep was had.
Cr@p photo, but my camera does not have a remote..........24.03.
PS. for those that know which water I am fishing, please note that it will be closed on Monday so that the weed can be removed and the water treated.
This will no doubt attract more anglers to the lake, but will the fish move from their present locations?
20/21-07-06