I wouldn't say it's a good pain, more like a reaffirming pain, as a reminder that HRT is working.

I can say with a four year old, who I love dearly, that I never get used to being head butted in the boobs when he gets excited and wants to give me a hug or snuggle. I ignore it so he doesn't feel bad, after all, he's just being my little sweetheart.
Amy