Did the OP try their pen on the other Surface device?? Agree though could be two from the same dodgy batch...
I am tempted by the 5k imac 27...!!
I know....madness, I'd just love that beautiful screen... But I could get a 4k Dell for around £500.. And my PC is better spec than the base imac 27" 5k...soooo I'll get over it...I think we on the forum will have to help you over this issue. It is time for a group MICROSOFT hug.
If the were a bad batch and both pens where from that batch, then very likely....