Update: I don't understand what caused Sudden Diastis Recti (photo)

Weight, and more particularly intra-abdominal fat that puts pressure on the abdominal wall are more likely causes of diastatis recti than your surgery. You could see your PCP for a good exam or scan to check for hernia in need of repair. If you are feeling recovery recovery difficulties from your surgery then it would be good to see him in person in order to get a full evaluation of any difficulties. So, it is hard to tell what you are dealing with until it is seen under exam and diagnosed by a physician. Best wishes!

Thank you for your update.  Diastasis recti, as you know, is a separation of the rectus abdominis muscles along the midline of the stomach.  Normally a condition that forms with significant weight gain or pregnancy, it indicates laxity of the tissues that normally keep the rectus muscles together.  It is difficult to say what may have taken place, but i would speak with your surgeon and continue to voice your concerns.  Immediate diastasis is not common, and as you had a surgery that entered into your abdominal cavity, best to rule out a hernia first and foremost.  If this is indeed a diastasis, then perhaps the surgical incisions resulted in exacerbating a preexisting laxity of the tissues.  Unfortunately sometimes we don't have an answer as to why something happened, which i understand is not a satisfying response.  There are ways to fix this, if you are interested, but another surgery would be needed.  

Thank you for your question.  Please have an in-person examination done by a surgeon.  That exam would indicate whether this "ridge" you see is a hernia or whether it is diastasis recti.  To me, it appears more likely to be a hernia, since it sits to the side of the belly button (not just above or just below it).  But there's no way to know for sure without a good personal exam.