I've had a number of guys recently put their stuff in the overhead bins, walk up to me and announce "Hey, I'm your Jumpseater"
This leaves me thinking "Are you telling me you're on the jumpseat or are you asking me if you can ride my jumpseat.....because there's a subtle but large difference".
I've commuted my entire career and this really isn't that hard. I don't care if the Captain acts like he doesn't need to see you. If you got on that plane by asking a Gate Agent if you can jumpseat (even if the G/A gives you some sort of seat assignment) stop by and request permission from the Captain and say Thanks. If that particular crew seems bothered, don't let that stop you from doing the same thing the next time you jumpseat.