The fact that the old guard seems to be doing just fine (albeit with a bit more effort) suggests that this is probably newbie error :)

As though the seller is lulling me to drop my guard.

Guthrie now lives in a rental a few blocks away.It’s in a safe neighborhood where private security guards patrol at night.

I don't know anyone who has done a deal this way, and was caught off guard when asked. 

Ryan, thanks for your response.Definitely working on getting debt paid down.You make a good point about guarding against the market cooling off where I currently live,  and I had not considered that.

I don’t want to just put a number or percentage in there and be caught off guard when I get to closing. 

I was just discussing this with @Jason Bott today and he mentioned a product called REI Guard. 

Ultimately I'll be a pilot in the National Guard, so we'll be back up in Massachusetts.We want to keep our current home, at least for the immediate future.

Like any smart investor, I cash those checks, stuff the money into a pillowcase, and guard it like Gollum. 

That clause generally applies more for those in the National Guard or Reserve who are activated for a long period of time (thus may have to take a leave of absence from a high paying job).