No, there is no problem if a floating voltage exists on the VCCL_GXB rail before it is ramped in Cyclone® IV GX devices. Leakage can occur between the VCCL_GXB and VCCH_GXB supplies which can cause VCCL_GXB to float to approximately 0.3V before the power supply is ramped up.
This is expected behavior and will not cause functional or reliability failures.
This can be observed if the VCCH_GXB supply is powered up before VCCL_GXB and the regulators were designed to leave the power supplies to float before they ramp up.