Front Axel vent tube

I was under my car today planning for a new skid plate and noticed that when the dealer did the last service on my front end, they left the front axel vent tube unplugged. I drove about 300 miles on it before noticing this and plugging it back in. - does anyone know if need to do something like add oil or something?

Unless you have been through deep water up to the opening, it should be fine. Open the fill hole, stick your finger in and see if the fluid is clear (good) or milky (bad).