I think since this is a first time for you, it's worth a call to your GI.
I will see blood every now and then but I know I have inflammation right at the rectum and it's typically just a bit of red when I wipe. So I don't bother to call.
When I first got sick 8 years ago I passed a lot of blood, and that was what got me to [finally] call the DR. The bleeding you saw Saturday is probably from some inflammation somewhere. Since you also had D it's possible you're flaring and need to change your meds.