I'm concerned that any interaction with OMW about this is unwarranted since you've already spoken to OM. In fact, IMO, unless the flames kick up again; I'd keep talking to OM at this point since he will take your calls.
You want to be careful with too many phone calls to either one of them. My gut says just keep using the info from your friend at her job to give you the temp of what is occurring there. If the need arises; then make contact.
This needs to be a balanced surveillance. You want her to come back and not see you as controlling. If you're controlling her every move but constantly calling OM and OMW about stuff you hear from your friend; she's going to get frustrated.
Plus, you want to be careful about calling someone else's wife. When I busted my W's A in '08 by calling OMW; once she went off on him, I left her alone. I didn't want to put myself in the position where are common source of misery becomes the ignition for our own EA or PA.
I'm not saying that you never call her again; but I would reserve that call for when you get intel that the flames have arisen again. If they're trying to work on the M; they don't need constant reminders from you about the source of their problems. Your friend at W's work should be able to give you what you need for monitoring your boundary.
Allen may disagree with me..I'm not sure. I just have to believe that there may be a point of diminishing returns of frequent phone calls to their house; especially if they feel their M is moving forward from this.
