Hi, theres two reasons that come to mind why this may be happening.
first your cervical cuff, the cuff that is made when cervix is removed to close top of vagina may have torn a bit , this would cause bleeding especially on exertion,.
second if your not using a lubricant during sex you may be tearing the vaginal walls, the natural lubrication is almost gone after a hyster.
In either case or if its something else you should most deffinatley see your gyno to find the cause of this...as you know red blood means fresh new blood, you need to find out why and what to do about it.
No, sorry, no similar experience...I never had bleeding after my hysterectomy.
I think this is worth a visit to the doctor, about.