Possible infection in bottle (anyone seen this before?)

Hi all. Sorry up front for not being able to put up a picture, the beer is in a brown bottle and any pictures I take don't show anything. I bottled a stout about ten days ago. I cracked one open last night and it tasted great, although under-carbed. I was gently swishing the bottles this morning when I noticed in one of them there was a lump of gooey white stuff at the bottom of one of the bottles. Then I started looked at the other bottles and I noticed that when I turned them upside down there was a gooeyish white substance that was on the bottom of the bottle and would stick to the surface of the beer when I turned it upside down. Has anyone seen this before? I am hoping that it is just the yeast and priming sugar combining to make some kind of ectoplasmic-esk reside or something. I did not notice it in the bottle I tried last night, but I also didn't look so there is no way to tell if that bottle had it. I would appreciate any insight you can give me. Thanks a bunch.