Probably not. I have transplanted Easter lilies many times with total success. Watch them. If the foliage doesn't perk up in a few days, cut it off. You may not get blooms next year but it's highly likely they'll live and bloom the next year after that.

As long as the foliage is green, it is photosynthesizing and converting CO2 into sugars and starches to feed the bulbs, whether it is laying on the ground or standing upright. I would leave it, until it turns yellow, at which time it no longer serves a purpose and can be removed.

When I lived there in the mid-1950's, there were a number of growers in Hamilton Parish (near the Swizzle Inn) that grew Easter lily's and many other types, for the cut-flower market. You didn't need a Rum Swizzle, as the flower fragances were so intoxicating!
(The Swizzle Inn was left to the tourists, the residents mostly frequented the White Horse in St. George and the Brass Rail (upstairs) in Hamilton).

Good luck with your Lilys!
Rb

Just to clarify, razorback is absolutely right. I didn't express what I meant very well at all. Do leave the foliage until it DIES (brown).