Dear James, any extra charging amps that are put into the battery that may be a little more than needed to affect the chemical reaction, will cause some electrolysis of the water in the electrolyte.
This means the water molecules will separate into hydrogen and oxygen, and seep out the vents. When removing the charging clamps, you may create a spark that can cause a suprisingly large blast near your face. I'm sure its even "possible" for a static charge from your fingertip to cause enough of a spark.
Best of luck, and be safe!