As airoaster2 says, probably a wing full of water. Try doing the roll the other way and see if anything comes out of the port wing.
I would point it out to whoever does the maintenance cos the paint should stop water getting into the wing (yeah right). If it's an ex-US Aerobat it probably isn't corrosion proofed and corrosion could be raising it's ugly head, unseen in your main spar. Mmmm now there's a thought. Wings clapping hands over your head is a sound you only hear once unless you have a large umbrella strapped to your bum.
Seriously though, the old Cessna is an overengineered little bird and it usually takes a long time for corrosion to be a problem; ie it should, I say again, should, be picked up at the Annual Inspection (looks at Luscombe owners with empty wallets after replacing their port main spars courtesy of intergranular corrosion- very rapid).
[ 31 January 2002: Message edited by: LowNSlow ]</p>