I had my bottom wisdom teeth taken out last week thursday (4 days ago). This morning I woke up with a "strained" (not sore) throat feeling - normal?

Wisdom teeth. Discomfort after removal of wisdom teeth is often dependent on how much bone was removed, the location of the teeth and whether they were vertical or horizontal. Some discomfort is normal, and may take several weeks to be totally pain free. Make sure you return to the surgeon for any scheduled post-op appointments. If you are having a problem, check with your surgeon.
Not unusual. After wisdom teeth extractions, there is a long healing period. As long as you are not having severe pain or swelling, it sounds like a normal result. If you feel that your jaw or jaw joint is strained then you might want to consult your dentist to see if the removal of your wisdom teeth has not altered your bite in a way to create TMJ problems.
Could be... Could be one of many reasons, including the start of a common cold, a dry socket, or so many other reasons. Call the surgeon that removed your wisdom teeth to check if they need to see you.