Good job starting minoxidil... and before starting propecia, try and understand the pharmacology and get blood tests to see where your hormones are before and after to find the best doseage. Too low of dht will cause issues, neurological, muscular and hormonal but if you find your sweet spot, you're set and will probably restore your thinning.
It looks like you caught it pretty early. See if the minoxidil does the job, then look into finasteride. Also, try eating pumpkin seeds every day. Pumpkin seed oil was shown to thicken hair of men with male pattern baldness in one study.
You seem to have caught it pretty early, aside from some minor thinning under the lights it's very hard to detect. Propecia would probably help your crown significantly but, first and foremost, do your research on it and make sure you make an informed decision whether it is right for you or not. There is a risk of sides with propecia (as with all prescription drugs) so make sure you weigh up that risk against your decision to fight your hair loss. I wish you all the best!
These are the changes that I've started noticing, too. Exactly this. I don't feel like my hair is falling out, but these differences, I feel, can't be ignored. I just started using Rogaine, so I'm not sure if I should be using anything else.