I suppose it is, if you think about bizarre pregnancy cravings. Soap, coal, chalk, cigarette butts and laundry detergent are, apparently, not uncommon cravings for women with child. They're not items you're likely to have tasted before in life. I didn't eat pasta until I was around fourteen years old (shocking, I know). The first time I did, it was because I suddenly had an overwhelming urge to make myself a bowl of pasta (with oodles of grated cheese and a bit of crispy bacon, in fact). I can't really explain this; I just knew I'd like it.
So it is really quite plausible that over the last few weeks I've had a huge craving for pumpkin pie.