<human>: Summarize the given text in a few sentences.

No throwaway because my fiance doesn't read reddit.

So my fiance and I have been together three years and met while in graduate school. He met my parents (divorced, but living in towns near one another) last Christmas (2013) when we stayed down in my home state for a week.  He spent some time with them again when I graduated from school this last May - basically, going to the ceremony and dinner with them. He and my parents hit it off really well, and both my parents absolutely love him. Both my mom and my dad will pass on messages ("Tell SO good luck on X") when I talk with them, and he'll have me pass on hello's in return. My mom has even started signing cards and texts with "Love you both" since we got engaged in September.

This May, he'll graduate with his PhD, and both of my parents have told me that they plan to show up and surprise him at graduation. Here's the thing: we're both pretty introverted people, and both of us tend to be a little socially anxious (not big fans of parties or giving speeches, for example). Aside from graduation and Christmas, there hasn't been a lot of contact between either of us and the other partner's family. Neither of us are super close with our families either or attend a lot of family events. My parents are thrilled that we're happy, and I know they want to celebrate his graduation because they're starting to see him as part of the family now that we're getting married. My mom's asked me to make reservations at a nice restaurant for dinner the night of graduation. I pointed out that his parents are coming and I don't know what they might be planning, but she wants me to make the reservation "so we have something to fall back on, just in case."

I'm worried that he'll be upset or anxious, and I don't know how he would react to that surprise. I'm not sure that I myself would be thrilled with his family showing up at an event like that without a heads up. Would you tell him?
<bot>: Fiance and I are introverted and a little socially anxious, and my parents (who he has met twice) want to show up and surprise him at his graduation. Should I give him a heads up?