I was recently Lobster hunting and around 80 ft had some difficulty getting a lobster out of a hole and into my bag. I wasn't paying attention and went into deco. My mares Puck Pro wrist computer had me do a 5-minute Deco stop at 10ft. When that was done it automatically went into a 3 minute countdown for a safety stop at 15 feet. Clearly I was not thinking and just surfaced. My thought at the time was that did not make sense to go back down to 15 feet for safety stop after I had just done a deco stop at 10ft. The computer then put me into lockout and went into surface timer mode. So I guess I have two questions. One is it normal to do a deeper safety stop after a 10 ft deco? And second if a safety stop is optional then why did it go into surface timer mode?