General reasons for extended soaking are:
Mites
Pre shed
Too low humidity
Too hot or too cold
Burns or other injuries and maladies
It's the only place they feel secure in the cage (may need a new hide)
A good soak for a day or two is ok but make that you check him over real good and double check his encloser - rule out all of the above or make any needed adjustments. If he continues to soak take the big bowl out and put a small one in so he doesn't get blisters.
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Tosha 
"One of these days i am going to wake up..look around...and realize my place looks more like "Ace Venturas"s than my own." Coldthumb
7.33.0 Ball Python (Harry and Fluffy and gang)
1.0.0 Angolan Python (Skywalker)
0.0.1 Green Tree Python
0.2.0 Feline (Pippen and Pandora)
0.0.1 Dessert Tortoise (Pope John Paul "JP"
2.2.1 Fish (1,2,3,4)
0.0.2 frogs rescued from pool skimmer
0.0.1 lizard rescued from vicious feline