Today when i got home i noticed that one of my cats had some liquid under one of his eyes. The liquid is clear. His eye is a little watery, but other than that he seems perfectly healthy. He's not sneezing or wheezing. His behavior hasn't changed in the least.
Is this something I should be concerned about?

Hi Kalena
One of my cats has eyes that water once in a while also. Sometimes they can get irritated by dust etc., just like in humans. If your cat is acting ok and eating I wouldn't worry about it. Just wipe your cats eye with a moist cotton ball and keep an eye on it. (no pun intended) Also if the clear discharge turns yellow or green or if you notice your cat squinting and not opening his eye then I would take him to the vet right away.

When my babies get "eye boogers", I wash the eye with a contact lens solution of sterile saline and boric acid- my vet said the balance of that product is perfect for this purpose and it rinses out whatever bit of dirt, hair or dander might be causing the irritation.

I wouldn't use a cotton ball, because it can leave threads in the cats' eye, making it worse. A piece of unscented uncolored un-lotioned toilet paper or tissue or paper towel is fine.
I wouldn't worry about it unless the color changes or it seems to start to bother him.
You could also use Neosporin or Polysporin to clear it out. Just dap a little bit in the corner with a clean fingertip. My mother did this to our cat, on the vets' advice, whenever she (the cat, not my mother) started to get eye goo. Worked like a charm.

Thanks for all the replies everyone. His eye was still watery this morning, but he's still eating and overall seems fine. I'll try rinsing his eye out and see if that helps.
Thank you again for your replies