It’s totally normal! Many people have the same reaction.
I’m not sure if this is the reason, but exercise releases a chemical called endorphins. Endorphins affect the receptors in your brain that reduce your perception of pain and they’re usually associated with a “happy” feeling/mood.
So if you’re feeling happy, less stressed, on a “high” from your workout, there’s no reason to think that wouldn’t influence your sex drive.
Also, working out has a positive influence on your self esteem. You feel more energized and better overall about your body image. So it’s really quite natural to feel “in the mood” after exercise. Your state of mind plays a huge part in it!