Grandpa isn't grumpy, he's just brutally honest. "Sometimes being too transparent can be a bad thing". Yes, because people will call you hater when their widdle feelings get hurt, but gramps is only telling the truth kids.
It's snappy replies working hard just to lead up to a pun, but what they hey, grandpa is funny and the house location is gorgeous. Well done, scout.
-"Grandpa, when did you know grandma was the one?"
"When her sister dumped me."