This is a great question. I am so glad you asked it Becky. I understand your apprehension. As an Ordained Southern Baptist Minister for over 25 years, I could speak for myself on how I would respond. I would be honored to meet your grandfather. I would love the fact that you respected me enough to introduce to me someone so special in your life.
I would not worry or stress about it. I am sure your new boyfriend would also look forward to meeting him. I am also confident that your grandfather would love to meet someone who is special in your life as well.
Philippians 4:6-7 do not be anxious about anything, but in everything by prayer and supplication with thanksgiving let your requests be made known to God.