That's pretty common. Sometimes a pair will spawn and the next day the nest is on the other side of the tank with all the eggs there too. I've never had it happen to me but alot of people have had it hapen to them.
Who am I? Well I am a Junior Member of the International Betta Congress and a breeder of white HMPKs, red dragon HMPKs, black/red dragon HMPKs, metallic multi HMPKs, blue masked HMPKs, and now multi color HMs. Soon to add black HMs. I will be showing in New Breeder class in fall of 2012.