iTunes Syncing Issue- "iPod is snyced to another computer" but it is not

After recently updating to the latest version of iTunes on my iMac, I am having an issue syncing with my classic iPods. I have 2 classic iPods with my music collection on them and when I plug them in through USB it tells me they are already synced to another computer and I keep having to wipe/resync them when I connect them to update with new music. It has done this twice now and I have not had this issue before. The iMac is the only computer I use for syncing the iPods and I am not having this issue with my iPhone or iPad. Any ideas? I should not have to go through this whole process every time I connect the iPods to add a newly purchased album to them.

I also updated to the latest Mountain Lion prior to having this issue if that makes any difference.

 

No, I only have 1 library. As far as I know at least, I am not familiar with using multiple libraries on the same system.