Ah, I ended up busting into it and taping. I was too nervous to sleep...

Well, it could have caused a problem with future phone reception if the exposed copper in the cut wires came into contact, but it's generally not a problem. The phone techs don't bother to tape: they just wrap cut -- but unused -- wires around the main cable so they are out of the way. If I were you, I'd have just put a blanking plate on the existing, old jack so I could find it more easily in a few years.

Thank you, Kudzu. I ended up taping it all up, just out of worries, and then drywalling over it again. I tried the blank plate, but it is in such an obtrusive place (the middle of the wall in the dining room), it was still unattractive to me.:P Thank you again for the information!