Nothing wrong at all. I wouldn't worry about it, unless your daughter herself has said something. The birth of (I assume to be) your first grandchild is a HUGE deal. I don't think any rational person would blame you for being as excited as you were when you became pregnant yourself! In fact, my dad once told me that the biggest surprise for him as a grandfather was that he loved his grandchildren just as much as he loved (and still loves) his own babies.
As a young(ish) mother, I can tell you that I take great joy in how close my parents and in-laws are to my children. I know that they literally ache to see my kids sometimes and that is a bond that I can share with them...it makes me love them even more.
The only conceivable problem I could foresee is the same one I've had with my in-laws on occasion. I don't think they've ever "re-invented" themselves as grandparents, as someone else put it, and that's caused some clashes between us when they haven't respected our wishes as parents (conceding to and respecting are two very different things, by the way).
My MIL thought she knew better than me on many issues (after all, she had a newborn too...30 years ago!) and saw my rules and preferences as being silly and over-bearing. As a result, she and my FIL became overly defensive...on everything. I mean, I couldn't so much as tell them to drive safely (when they were taking my son somewhere) without them getting offended.
It made me feel uncomfortable around them for a long time. I felt like they were judging me, and finding me lacking. It felt like we were strangers for a while, like the whole dynamic of our relationship had changed, because they couldn't stop seeing me as "the child" or even "the equal" and start seeing me as "the mother." There was simply a lack of respect there, because they'd never been in the position to respect someone so much younger (and less experienced) than them.
So my advice is to give all of the love and support that you have within you to give. Be as close to your beautiful grandbaby as you possibly can be (and certainly anticipate the due date with all of your heart!) But when baby comes, try and remember to respect your daughter's status as "mother" and respect the fact that she's new at this and will be traveling her own path of motherhood...which might look very different than yours did.
New moms are extremely uncertain, so whenever she's freaking out, try to reassure her and tell her she's doing great and things will get better. Offer advice ONLY if it's asked for and don't be pushy or insistent about it.
Your daughter will probably need you a LOT in the early days, but she'll come to depend on you a great deal after that if you play your cards right and offer kind, reserved, non-judgemental support. Sort of an "I'm here for you, but you're the boss" kind of attitude.
Best of luck to you and congratulations!
-S.
P.S. If you want to really be the best grandma (and mom) ever, I suggest reading some current material on baby-proofing your home and get started right away. Moms are a lot more safety conscious nowadays, so having your house ready to go will avoid a lot of awkward conversations and make your daughter more likely to bring the baby for visits.