Yeah, thats what my laptop does all the time too mostly, and I'm now wondering if the unit overcharges this way, and that hastens the problem as well.

You mentioned the battery cycle count was 58 - that number normally starts at 1 the first time you install it in the laptop and power it up on AC and counts up for each charge "cycle" from then on, so your battery thinks it had 58 discharge and charge cycles.

Question is how much of a "discharge" is needed from 100% to make the battery think a cycle has occured? More than 10%?

That may be part of the problem - you have to run it down every now and then, but not too much - but I don't know what "not too much" is for a Li-Ion battery and IBM wasn't much help either!