'Tis possible she wet it again on purpose to explicate her alibi. If it is wet, we are more inclined to believe she did, in fact, go for a swim; she may have admitted to being at the pool that night due to its public nature. Any of us could pass by and see her there, so to admit it would cast suspicion away from her, turning her attempts to douse the boy's head into a harmless, meditative venture.