I had a collapsed lung and I have a chest tube on me right now. I'm wondering if it's normal if the tube is filled with a redish liquid?

Why put in? The answer somewhat depends on the cause of the collapsed lung and the method the tube was inserted, how long ago, and if the red color is getting better or worse.
Discuss w your doc. It would be expected to have a little blood in the pleural fluid right after the chest tube is placed. Depending on the causes of how your lung is collapsed, a little blood that makes the fluid look reddish can be expected or it is a cause for concern. Best way is to discuss it with your attending physician or your floor nurse. Hope you have a quick recovery.
Not unusual. It is not unusual to have some blood in the chest tube. Frequently, particularly in the case of trauma, there is a hemo-pneumothorax. That is, there is blood also in the space between the lung and the pleural space. This is effectively drained by the chest tube.