Are you sure it was her muscus plug she lost? it seems a bit early. i am moving this to a more appropriate forum for you.

she is 90% that it was a mucus plug but there was no blood with it. this is her 6th pregnancy the other 5 where all o.k. the baby is moving and kicking as normal and there are no other signs of laber or any thing

It could have been sperm left inside her, since you say you had sex the night before. Mucous plugs can be lost and grow back many times before labor. It can mean something ~ but then again, it might not. Sex is fine until her water breaks.