I have had a couple of mild bouts of diverticulitis over the years and have noticed that my bladder seems to get irritatated too. i end-up urinating more. is this normal?

It is possible for the bladder to be irritated by inflammation nearby, e.g. if there is active diverticulitis adjacent to the bladder. This can cause increased urinary frequency and urgency, in the same manner as overactive bladder. If the problem clears when your diverticulitis improves, I wouldn't worry about it. If it persists, discuss with your doctor.

If the diagnosis of diverticulitis is correct and the area is near or touching the bladder it can give these symptoms by irritating the bladder