This is usually a condition that can develop when using a Form B or normally closed reed relay. The contacts are biased closed with a magnet. So with no power on the coil, the contacts remain closed. When power is applied to the coil, its magnetic field is opposite the field of the magnet cancelling it out and opening the contacts. If the coil is too strong, the contacts can reclose. So a reclose voltage is added to a Form B relay that is usually 25% to 50% above the nominal voltage. For a 5 volt relay with 50% safety factor the reclose would be 7.5 Volts. This guarantees to the customer that applying up to 7.5 Volts the contacts will not reclose.