EMB-170 Captain reported inadvertently flying an aircraft with an improper sign off involving a bent fan blade.

Narrative

I operated Flight ABCB from ZZZ to ZZZ1. After arrival into ZZZ1; ramp agent brought to my First Officer attention an issue with the aft cargo door. Also the next crew taking over the aircraft was present and the Captain graciously offer to do the write up so we could go to our overnight. We blocked in at XA27am local. At XD38pm the Captain called to explain an issue with the aircraft that I had noted when I accepted the aircraft in ZZZ. He had previously written up a bent fan blade the previous night in ZZZ1 on log page X. In the corrective action block noted 'Performed visual inspection in accordance with GE LMM dent noted found to be previous rework (this word was written sloppily) aircraft OK for service. So since Captain that was taking over aircraft had previous knowledge of this particular write up; he questioned the sign off. He called me to let me know that this was improperly signed off and indeed this blade was out of tolerance.So essentially I unknowingly flew an aircraft that was out of tolerance but reviewing the write up and sign off; I can only assume it was fixed properly.