Indian Star Tortoise behavior

My Indian Star Tortoise (captive bred; four years old) has recently developed the habit of spending hours in his water bowl soaking. Since getting him (three months ago) I have been soaking him daily for 15 minutes before his breakfast, but now he is taking himself off for long soaks every day. Is this normal? His enclosure is not too hot. It is always between 80F and 85F. Thanks so much.