Reality Check on Mortgage Broker Behavior?

[Jason V.]

Quick background: I'm selling one of my SFRs, buyers are using a mortgage broker to get a USDA loan, which I believe is a 0% down. No RE agents involved. We agreed on the sale price, and 6% seller concessions. 

Now we're about 2 weeks out from the originally scheduled closing date, and the mortgage broker sent me an email saying the appraisal just came in, and we're going to have to lower the sale price by 6% (and still do 6% seller concessions) in order to proceed. 

I asked for a copy of the appraisal, and he said no. When I pressed him on it, he told me "The appraisal is good, they did 6 comps, and I know this appraiser - they are good." I'm still not buying it, and I know of at least a couple of sales in the area that had extenuating circumstances that lowered their sale prices 20-30%. 

He is also refusing to send a copy of the appraisal to the buyers (who I have a very good relationship with) until after he receives a signed addendum, updating the sale price. 

Does this make anyone else's Spidey Sense tingle? 

Due to a lot of other information I don't need to go into, I'm pretty much locked in on this sale - I'm just wondering if I'm getting played here, or if this is typical. 

Even if we do the addendum to lower the sale price, I'll eventually get my hands on a copy of the appraisal, so the broker can't be banking on me being an idiot...right?