Clipless Pedals = Quad Burn? Need some help

Have you had your whole bike fitted, or just the pedals?
It makes a difference.
Your quads are going to do most of the work, so it may just be a case of getting used to the change. It is very difficult to give fit advice over the internet. However, this sounds like it may be a fit issue.

I'm a recent convert to clipless, and have noticed just the opposite.  I feel that I'm using my hamstrings much more (especially on the hills) from being able to pull up on the pedals. 

When I bought the bike last month, it was fitted and seemed fine the whole time I've been riding it until I got the clipless pedals. Maybe it is just an issue of getting used to them. I think I'll give it a week or two, and if there is not improvement, I can go back to the LBS and see if some adjustments can be made

If the bike shop didn't already do it, you may have to adjust your seat up just a tad. Clipless pedals have a different "stack height" (the difference between the bottom of your foot and the centerline of the pedal spindle) than platforms with toe clips. Probably a bit higher, in most cases. This won't seem like much, but it can make a difference in how your leg muscles are engaged.

Which type of pedals did you get?

Try raising your seat about 1/4" and see if it helps.

I wouldn't go any more than that if the bike was properly fitted before you added the clipless pedals. If you change it by more, you'll start affecting the fore/aft seat position, reach to the bars and all that, and you'll have to start over from scratch with the fit. Even with 1/4", you might have to shift the seat forward just a skosh, depending on how it feels.

:-)

When I bought my bike they adjusted my bike (it had the clip pedals). Once I got the clipless pedals a week later they had to re-adjust the whole bike (not only the pedals). They realized they had to change the saddle and the stem. Go bak to your LBS and let them know.

I noticed the same thing you did when I first got clipless pedals. I think the reason had to do with where my foot was placed over the pedal axle. The center of the pedal axle should be underneath the ball of your foot.
Previously when I had platform pedals and toe straps, the pedal axle was underneath a point slightly forward of the ball of my foot.

Also if the saddle was to high to begin with, then you may have been pointing your toes (thus invoking the lower leg muscles) to complete the pedal stroke.
Most people keep their ankles in a somewhat neutral position, although there is a pedaling style called "ankling" that does the opposite.