It's uncommon, but not unheard of.There is no paperwork proving that a service dog is an actual service dog. 

But, it's not unheard of to have a service that must enter every month, is my point.And in your situation, your tenant is basically demanding you provide the service.  

It is not unheard of that tenants who sneak out on a lease/rental property will turn around and sue their former landlord because they did not receive information regarding their security deposit.Gail

There are PMs on this forum who only charge flat fees, so it's not unheard of. 

You didn't ignore his concern (All this is assuming you aren't lying to us about the real facts of the case which is not unheard of so no offense to you I hope).  

Not sure if this is the case nationwide, but in Tucson AZ, we've found that Truly Nolan provides the best price on bedbug treatments, but the biggest benefit is that they offer a 1 year warranty on the treatment, which is unheard of with any other pest control companies.

I have some tenants paying rent that is simply unheard of and a few years ago was so low it impacted our taxes because it was not "market rate".

Not unheard of but I should mention the SFH with 15% down purchase is a 30 yr fannie mae mortgage with interest rate 5.25 and the 20% down duplex purchase was through a portfolio lender who keeps loans in house--15/30 mortgage, no reserves for properties with them,  no escrow, DSCR 1.3 or higher, the interest rate being near an owner occupied home rate. 

In my area $2k em is unheard of IMO on lower income properties.

No one took responsibility for this appraiser and his work, as being that far off is unheard in Atlanta.