While there may not be a power-sequence requirement in the sense of particular supplies coming on before others. The Altera handbooks (and implementation guides) usually have a statement to the effect that all power rails must come up monotonically and be stable within the power-on-reset time of the device.
Since you mention you are using a GX device, I assume you are using the transceivers. If you are using this device in a PCIe design, then you have a power-on requirement for the PCIe end-point to be alive within about 100ms of power-on. This means that you need to factor in the time for your power supplies to power up.
Here's an example for you to read through
http://www.ovro.caltech.edu/~dwh/wbsddc/ts4_power.pdf Cheers,
Dave
