The last time I heard of any limitations like this it was from a guy who made a massive video of about 74 hours. He said that while doing this he found that most NLEs have a limit of either 12 or 24 hours. So we can discount a limitation of one hour audio in Vegas.
If you're using FAT32 would that make your recording software split the file into 4Gb sections ? There is one option that I know of in Vegas which is something to do with wave files and 4Gb limit. This is described in the Vegas help as:
Select this check box to enable support for WAV files up to 4GB before switching to WAV64. Clear the check box for compatibility with other software applications.
AND there is and other option called "Render large Wave files as Wave64" which says in the help about it: The .wav format is limited by a maximum file size of ~2GB (4GB if the Allow Wave renders up to 4 GB check box is selected). When this check box is selected, you can render larger files as Sony Wave64 files.
I don't really know if this is relevant to your situation but it's the only info I know about this sort of thing.