Dog food over treats?

When I leave for work I give Riggs a treat.  Today Riggs had no interest in his treat so I just laid it on top of his bowl of dog food so he can eat it later.  When I got home tonight I noticed something strange with his food bowl.  He ate all his dog food but left the treat in there.  Apparently it is time to find some new treats.  Riggs appears to be burnt out on the pumpkin animal cracker treats.