I have seen really red feet 3 times - in one of the gliders, his feet began to swell soon after they were noticed to be red. This glider had a staph infection which took a LONG time to recover from and the glider almost died several times.
Both of the other times I have seen it, the glider was having an allergic reaction - one to the fabric soap being used and the other to a material used in a toy in the cage.
I would have your little one checked out immediately. I would also remove EVERYTHING from the cage and replace it with stuff that you KNOW the glider is not having issues with - you may have to slowly do a process of elimination, but you don't want her to have long time exposure to something she may be allergic to.
Bright red feet/hands are NOT normal. You are right to be concerned.