I tend to agree with Maurice Sendak,
People said, "why didn’t you do Wild Things 2? Wild Things 1 was such a success!" Go to hell. Go to hell. I’m not a whore.
but seriously though, do you WANT to do a full series? When people say "oh man I'd read a full series of this," does it make you think "whoa, it's awesome to know there's an audience for this because I'd really love to do a story like that!" or "oh man, I didn't even think of doing this but holy crap what a good idea!" ...... or does it make you think "well.... I mean, I probably COULD make a full series out of this.....I don't mind.......I guess I should keep it going?"
Because if it's that last one, I'd say no. If you're only in it because the readers want it, it's gonna be hard to tell a good story while trying to guess what exactly it was that they wanted -- and a story that isn't fun for you isn't fun for your readers, either.
I got a lot of the same sort of reactions you're getting when I announced I was ending my journal comic, Today Nothing Happened, after 4 years. People don't like things to end! From my readers' point of view, they wanted it to continue because they wanted more comics at the same quality that were just as funny. From my point of view, that was going to be hard to do, because while I loved TNH, my heart was now in other things. So I ended it and gave it a proper farewell, and I definitely don't regret that decision!